Hex key

A hex key, Allen wrench or Allen key, is a simple tool used to drive bolts and screws with hexagonal sockets in their heads.

The tool is usually formed of a single piece of hexagonal rod of hard steel, with blunt ends that are meant to fit snugly into the screw's socket, bent in an "L" shape with unequal arms. The tool is usually held and twisted by the long arm, creating a large torque at the tip of the short arm. Reversing the tool lets the long arm reach screws in hard-to-reach places.

Each key is meant to be used with screws of a specific socket size, with rather tight tolerances; so the tool is commonly sold in kits that include half a dozen or more keys of different sizes. Usually the size of the key increases with the size of the socket, but not necessarily in direct proportion.

Variants of the tool have the short end inserted in a transverse handle, which may contain multiple keys that can be folded into the handle when not in use.

The "Allen" name is a registered trademark, originated by the Allen Manufacturing Company of Hartford, Connecticut circa 1910, and currently owned by Apex Tool Group, LLC. The standard generic name used in catalogues and published books and journals is "hex key".

Allen keys
Hex keys of various sizes
Socket head screws of various sizes
Same hex key, different screw threads


Explained by the geographical and commercial history of the drive type's development, the term "hex key" is best known as "Allen" in the USA (The “Allen” name is a registered trademark, originated by the Allen Manufacturing Company of Hartford, Connecticut circa 1910, now owned by Apex Tool Group, LLC, which was acquired by Bain Capital in 2014), and also in Spain (llave Allen pronounced with Spanish double L, /ʎaβe aʎen/), as "Inbus" in Germany (the term “INBUS” is a registered trademark, originally an acronym for Innensechskantschraube Bauer und Schaurte introduced in 1934 by the German company Bauer & Schaurte, in 2015 acquired by INBUS IP GmbH, Breckerfeld, Germany),[1] and as "Unbrako" key or wrench in Scandinavia (originally a Pennsylvania company established in 1911, in 2008 acquired by Deepak Fasteners Limited).[2] In Italy, it is known as brugola, for the company Officine Egidio Brugola (established 1926).

The term "hex-head" is sometimes used to refer to this type of drive, but this use is not consistent with its more conventional use referring to external-wrenching hexagons.


Some features of hex keys are:

  • The tool is simple, small and light.
  • The contact surfaces of the screw or bolt are protected from external damage.
  • There are six contact surfaces between bolt and driver.
  • Very small bolt heads can be accommodated.
  • The tool allows the use of headless and recessed-head screws.
  • The screw can be held by the key while it is inserted into its hole.
  • The torque applied to the screw is constrained by the length and thickness of the key.
  • The tool is very cheap, so it can be included with products requiring end-user assembly.
  • Either end of the tool can be used to take advantage of reach or torque.
  • The tool can be reconditioned using an electric grinder by removing the worn-out part near the end.
  • High torque is more likely to damage an internal socket/key than an external hexagon head/wrench
  • It is much more difficult to turn a damaged internal fastener than an external one.


Allen Mfg Co Inc 1913 advert in Auto Trade Dir
Allen Manufacturing Company Inc advertisement for the Allen Safety Set Screw, a brand of set screw, in the Automobile Trade Directory, January 1913.

The scant documentation available indicates that the idea of a hex socket screw drive was probably conceived as early as the 1860s to the 1890s, but that such screws were probably not manufactured until around 1910. Rybczynski (2000) describes a flurry of patents for alternative drive types in the 1860s to the 1890s in the US,[3] which are confirmed to include internal-wrenching square and triangle types (that is, square and triangular sockets) (U.S. Patent 161,390), but he explains that these were patented but not manufactured due to the difficulties and expense of doing so at the time. P. L. Robertson, of Milton, Ontario, Canada, first commercialized the square socket in 1908, having perfected and patented a suitable cold forming method, using the right material and the right die design.

In 1909–1910, William G. Allen too patented a method of cold-forming screw heads around a hexagonal die (U.S. Patent 960,244). Published advertisements for the "Allen safety set screw" by the Allen Manufacturing Company of Hartford, Connecticut, exist from 1910.[4] Although it is unlikely that Allen was the first person to think of a hex socket drive, his patent for a manufacturing method and his realized product appear to be the first.

In his autobiography, the founder of the Standard Pressed Steel Company (SPS; now SPS Technologies, Inc.), Howard T. Hallowell Sr, presents a version of events[5] in which SPS developed a hex socket drive in-house, independently of Allen, circa 1911. From this came the Unbrako line of products. This account from Hallowell does not mention the Allen patent of 1910, nor the Allen safety set screw product line. Hallowell does describe, however, the same inspiration also mentioned in connection with Allen for a wave of adoption of the hex socket head, beginning with set screws and followed by cap screws. This was an industrial safety campaign, part of the larger Progressive Movement, to get headless set screws onto the pulleys and shafts of the line shafting that was ubiquitous in factories of the day. The headless set screws would be less likely to catch the clothing of workers and pull them into injurious contact with the running shaft.

SPS at the time was a prominent maker of shaft hangers and collars, the latter of which were set in place with set screws. In pursuit of headless set screws with a better drive than a straight slot, Hallowell said, SPS had sourced set screws of square-socket drive from Britain, but they were very expensive.[6] (This was only 2 years after Robertson's Canadian patent.) This cost problem drove SPS to purchase its first screw machine and make its screws in-house, which soon led to SPS's foray into fastener sales (for which it later became well known within the metalworking industries). Hallowell said that "[for] a while we experimented with a screw containing a square hole like the British screw but soon found these would not be acceptable in this country [the U.S.]. Then we decided to incorporate a hexagon socket into the screw […]."[7] Hallowell does not elaborate on why SPS found that the square hole "would not be acceptable in this country", but it seems likely that it would have to have involved licensing Robertson's patent, which would have defeated SPS's purpose of driving down its cost for internal-wrenching screws (and may have been unavailable at any price, as explained at "List of screw drives > Robertson"). The story, if any, of whether SPS's methods required licensing of Allen's 1910 patent is not addressed by Hallowell's memoir. The book does not mention which method—cold forming or linear broaching—was used by SPS in these earliest years. If the latter was used, then Allen's patent would not have been relevant.

Soon after SPS had begun producing the [hex] socket head set screw, Hallowell had the idea to make a [hex] socket head cap screw (SHCS). Hallowell said, "Up to this moment none of us had ever seen a socket head cap screw, and what I am about to relate concerns what I believe was the first socket head cap screw ever made in this country [the U.S.]."[8] SPS gave their line of screws the Unbrako brand name, chosen for its echoing of the word unbreakable.

Hallowell said that acceptance of the internal-wrenching hexagon drive was slow at first (painfully slow for SPS's sales), but that it eventually caught on quite strongly.[9] This adoption occurred first in tool and die work and later in other manufacturing fields such as defense (aircraft, tanks, submarines), civilian aircraft, automobiles, bicycles, furniture and others.

Concerning the dissemination of the screws and wrenches, Hallowell said that "the transition from a square head set screw [Hallowell refers here to the then-ubiquitous external-wrenching square drive] to a hexagon socket head hollow set screw[,] for which had to be developed special keys or wrenches for tightening or loosening the screw, was the cause of more profanity among the mechanics and machine manufacturers than any other single event that happened. […] I am sure that the old-timers who read this book will remember this period vividly."[10] (These transitional growing pains echo those experienced many decades later with the adoption of the Torx drive).

World War II, with its unprecedented push for industrial production of every kind, is probably the event that first put most laypersons in contact with the internal-wrenching hexagon drive. (Popular Science magazine would note in 1946 that "Cap screws and setscrews with heads recessed to take hexagonal-bar wrenches are coming into increasing use.")[11]

It appears that the internal-wrenching hexagon drive may have been independently reinvented in various countries. At the least, the design (or methods of manufacturing it) was patented in various countries by various patentees, and its name varies. There is another name in Italian (brugola), stemming from the name Officine Egidio Brugola, a company who first commercialized Allen's products in Italy.

Hex key standard sizes

Hex keys are measured across-flats (AF), which is the distance between two opposite (parallel) flat sides of the key.

Using a hex wrench on a socket that is too large may result in damage to the fastener or the tool. An example would be using a 5 mm tool in a 5.5 mm socket. Because hex-style hardware and tools are available in both metric and Imperial and customary sizes (the latter sometimes labelled "SAE"), it is also possible to select a tool that is too small for the fastener by using an Imperial/customary tool on a metric fastener, or the converse. There are some exceptions to that. For example, 4 mm keys are almost exactly the same size as 5/32", and 8 mm keys are almost exactly the same size as 5/16", which makes 4 mm and 8 mm preferred numbers for consumer products such as self-assembly furniture, because end users can successfully use an imperial key on a metric fastener, or vice versa, without stripping. 19 mm keys are so close to the same size as ¾" that they are completely interchangeable in practical use.

Metric sizes

Standard metric sizes are defined in ISO 2936:2014[12] "Assembly tools for screws and nuts—Hexagon socket screw keys", also known as DIN 911, and, measured in millimeters (mm) are:

  • 0.7, 0.9, 1.0, 1.25, 1.3, 1.5
  • 2 to 6 in 0.5 mm increments, sometimes incorrectly referred to as M2 to M6 which rather should refer to thread sizes (see below for M1, M2 style designation).
  • 7 to 22 in 1 mm increments
  • 24, 25, 27, 30, 32, 36, 42 and 46 mm.

Metric hex wrench sizes are sometimes incorrectly referred to using the designation "M" followed by the size in millimeters of the tool or socket, e.g. "M6", although this may be confused with the standard use of "M6" which refers to the size of a metric screw or bolt.

Table of some common metric hex key sizes from 0.7 to 10 mm. Italic values are rounded.
1st choice 2nd choice Inches
0.7 mm 0.028"
0.9 mm 0.035"
1 mm 0.039"
1.25 mm 0.049"
1.3 mm 0.051"
1.5 mm 0.059"
2 mm 0.079"
2.5 mm 0.098"
3 mm 0.118"
3.5 mm 0.138"
4 mm 0.157"
4.5 mm 0.177"
5 mm 0.197"
5.5 mm 0.217"
6 mm 0.236"
7 mm 0.276"
8 mm 0.315"
9 mm 0.354"
10 mm 0.394"

1st choice column shows some of the sizes which are most commonly found on hex screws with ISO metric threads (M-threads)[13]
2nd choice sizes are rarely used.

Inch sizes

American sizes are defined in ANSI/ASME standard B18.3-1998 "Socket Cap, Shoulder, and Set Screws (Inch Series)".

Table of some common SAE hex key sizes from 0.028" to 3/8". Italic values are rounded.
Inch size Millimeters Inches
0.028" 0.71 mm 0.028"
0.035" 0.89 mm 0.035"
0.050" 1.27 mm 0.050"
1/16" 1.59 mm 0.0625"
5/64" 1.98 mm 0.078125"
3/32" 2.38 mm 0.09375"
7/64" 2.78 mm 0.109375"
1/8" 3.18 mm 0.125"
9/64" 3.57 mm 0.140625"
5/32" 3.97 mm 0.15625"
3/16" 4.76 mm 0.1875"
7/32" 5.56 mm 0.21875"
1/4" 6.35 mm 0.25"
5/16" 7.94 mm 0.3125"
3/8" 9.53 mm 0.375"

Note that numerous other sizes are defined; these are the most common.


Allen wrench with ball end 1
Hex keys of various sizes with ball ends.

A security version of the hex head includes a pin in the center. These fasteners are said to have a "center pin reject" feature to prevent standard hex wrenches from working. A special driver must be used to fasten or remove these fasteners. The TORX head's security variant also has such a pin for the same reason.

Some hex keys have a ball on one end, which allows the tool to be used at an angle off-axis to the screw. This type of hex key was invented in 1964 by the Bondhus Corporation,[14] and is now manufactured by several other companies.

While providing access to otherwise inaccessible fasteners, thinning of the tool shaft to create the ball shape renders it weaker than the straight-shaft version, limiting the torque that can be applied. The tool also makes point contact with the fastener as opposed to the line contact seen in the straight style tools.

Manufacturing methods

  • Hex socket screw heads are usually made by stamping the head with a die, plastically deforming the metal. Other ways to generate the hex socket include linear broaching and rotary broaching. Broaching the heads with a linear broach is essentially the metalworking analog of mortising wood with a mortising machine; a hole is drilled and then the corners are broached out. This operation often leaves little telltale curled chips still attached at the bottom of the socket. These are negligible for most applications.
  • Hex keys are made by imparting the hexagon cross-section to steel wire (for example, with a drawing die), then bending and shearing.

See also


  1. ^ INBUS IP GmbH, Breckerfeld, Germany was registered on 27 August 2015 (Amtsgericht Hagen Aktenzeichen: HRB 10066), formerly Fabelhaft Werkzeug UG. Fabelhaft Werkzeug acquired the trademark from RT Holdings III WG (US), LP, Luxembourg, on 24 July 2015. INBUS IP GmbH was registered with the stated purpose of holding and licencing the trademark INBUS. In late 2015 to early 2016, the company sent out desist orders to companies using the name "Inbus" for hex keys. M. v. Hohenhau, [1] (fachanwalt-it.blogspot.com) Abmahnung Fabelhaft Werkzeug UG (ratgeberrecht.eu, 26 November 2015). Abmahnung INBUS IP GmbH (ratgeberrecht.eu, 15 January 2016). Hex keys with the INBUS brand are now manufactured at HaFu Werkzeugfabrik H. J. Fuhrmann GmbH, Breckerfeld, North Rhine-Westphalia, as of 2017 accounting for 7% of the company's EUR 8 million turnover. Jens Bergmann, Inbus-Schlüssel (brandeins.de, 2018).
  2. ^ unbrako.com; Varumärke - UNBRAKO (solidinfo.se)
  3. ^ Rybczynski 2000, pp. 79–81.
  4. ^ Alloy Artifacts, Various Tool Makers (section on Allen Manufacturing Company), archived from the original on 2011-12-30, retrieved 2012-01-25.
  5. ^ Hallowell 1951, pp. 51–52.
  6. ^ Hallowell 1951, p. 51.
  7. ^ Hallowell 1951, p. 52.
  8. ^ Hallowell 1951, p. 57.
  9. ^ Hallowell 1951, pp. 54,57–59.
  10. ^ Hallowell 1951, p. 54.
  11. ^ https://www.iso.org/standard/60231.html
  12. ^ MARYLAND METRICS - TECHNICAL INFORMATION and DATA - Hexagon sockets (DIN 912, ISO 4762, DIN 6912, DIN 7984, DIN 7991, DIN 913, 914/5/6, ISO 4026, 4027/8/9, ISO 7379, ISO 7380, K 323)
  13. ^ Premiere ball end tools, Bondhus Corporation, archived from the original on 2006-03-19


External links

Allen (Prison Break)

"Allen" is the second episode of the first season of the television series Prison Break, which was first broadcast on television on August 29, 2005. The episode is the second to air alongside the Pilot episode as part of the two-part start of the series. "Allen" was written by series creator Paul Scheuring and directed by Michael Watkins. Robert Knepper makes his first appearance as Theodore "T-Bag" Bagwell, but was not yet billed as a regular character until the following episode, "Cell Test". Also, Marshall Allman, despite credited, does not appear as L. J. Burrows.

The episode's title refers to the hex key that Michael makes from a screw, the key being named "Allen Schweitzer 11121147". Also in this episode, Veronica Donovan continues her investigation as to who is actually responsible to framing Lincoln Burrows on Michael's request, while at the same time, Michael deals with the impending race riot in Fox River, which could hinder his escape plans.

Beretta Pico

The Beretta Pico is a small, semi-automatic pistol intended for concealed carry.

Bicycle lock

A bicycle lock is a security device used to deter bicycle theft, generally by fastening the bicycle to a fixed object, e.g., a bike rack.

Quick-release levers, as used on some bicycle wheels and seatpost fasteners, are a security vulnerability, because they allow the wheels and saddle to be easily removed. Unless such easily-removable components are secured while the bicycle is unattended, they are vulnerable to theft. Sensible locking strategies address this by locking these components in addition to the frame, or by taking the vulnerable components, such as quick-release front wheels, away from the bicycle.

Locking devices vary in size and security, the most secure tending to be the largest, heaviest and least portable. Thus, like other security equipment, bicycle locks must balance the competing interests of security, portability, and cost. Some are made of particularly expensive materials chosen for their acceptable strength and low density.

An alternate defense is the provision of bicycle lockers or a bike cage in which the whole bicycle is locked, but these are uncommon in some countries. A bike locker is not a bicycle lock.

Test standards that rate the effective security of bicycle locks are provided by Thatcham and Sold Secure in the United Kingdom, ART in the Netherlands, SSF in Sweden, and VDS in Germany. Tests carried out by the Cyclists' Touring Club showed that all of the locks under test could be broken in less than 42 seconds using either bolt cutters for a cable/chain or a bottle jack for D-locks.


The bodhrán ( or , Irish pronunciation: [ˈbˠəʊɾˠaːnˠ]; plural bodhráin or bodhráns) is an Irish frame drum ranging from 25 to 65 cm (10–26 in) in diameter, with most drums measuring 35–45 cm (14–18 in). The sides of the drum are 9–20 cm (3 1⁄2–8 in) deep. A goatskin head is tacked to one side (synthetic heads or other animal skins are sometimes used). The other side is open-ended for one hand to be placed against the inside of the drum head to control the pitch and timbre.

One or two crossbars, sometimes removable, may be inside the frame, but this is increasingly rare on modern instruments. Some professional modern bodhráns integrate mechanical tuning systems similar to those used on drums found in drum kits. It is usually with a hex key that the bodhrán skins are tightened or loosened depending on the atmospheric conditions.


A chinrest is a shaped piece of wood (or plastic) attached to the body of a violin or a viola to aid in the positioning of the player's jaw or chin on the instrument. The chinrest may be made of ebony, rosewood, boxwood, or plastic. It was invented by Louis Spohr in the early 19th century; historically, this has been explained as a response to increasingly difficult repertoire which demanded freer left hand techniques than had previously been used; however, Spohr intended his small block attached to the bout to protect the tailpiece, which he reportedly broke with his vigorous playing. However, after being promoted by prominent violinists of the day, such as Pierre Baillot and Giovanni Battista Viotti, it gained quick acceptance among most violists & violinists and is today considered a standard part of the viola and violin.

Coffin lock

Coffin lock is a slang term for a blind panel connector (also called a butt-joint fastener) often used in scenic construction to join together stage decks or scenery in a butt joint. These are two part connectors (male and female) that draw together and lock. The two most common types are the cam and acceptor and more traditional hook and pin version. These devices generally use a hex key to operate the locking mechanism via a small diameter hole either through the face or rear of the panel. When locked, the considerable mechanical advantage offered by the cam or hook holds the panels tightly together. Coffin locks can be installed directly into a mortise cut into each panel for total concealment except for the locking hole or mounted to the rear of the panels. Many small theatres use stock platforms with coffin locks built into the frames.


A freehub is a type of bicycle hub that incorporates a ratcheting mechanism, and the name freehub is a registered trademark of Shimano. A set of sprockets (called a "cassette") are mounted onto a splined shaft of the freehub to engage the chain. The ratcheting mechanism is a part of the hub, in contrast to a freewheel, an older technology, which contains both the sprockets and a ratcheting mechanism in a single unit separate from the hub. In many high-end and midrange bicycles, freehubs have replaced freewheel systems.

A freewheel mechanism allows a rider to stop pedalling whilst the cycle is still in forward motion. On a cycle without a freewheel mechanism, the rider has to keep pedalling whenever the cycle is moving.

Klein Tools

Klein Tools is an American company based in Lincolnshire, Illinois that manufactures hand tools. The company is known for its popularity with workers in the electrical and telecommunications industries. Lineman's pliers are often called "Kleins," an example of a genericized trademark.

Klein's line-up contains more than 3,800 different tools, including 165 different types of pliers, in addition to screwdrivers, nut drivers, wire pulling and stripping tools, crimping tools, scissors, snips and shears, cable and bolt cutters, conduit benders, personal protective equipment, and tool bags. Klein produces a high-end line of tools under its Journeyman label.

List of screw drives

A screw drive is a system used to turn a screw. At a minimum, it is a set of shaped cavities and protrusions on the screw head that allows torque to be applied to it. Usually, it also involves a mating tool, such as a screwdriver, that is used to turn it. The following heads are categorized based on commonality, with some of the less-common drives being classified as "tamper-resistant".

Most heads come in a range of sizes, typically distinguished by a number, such as "Phillips #00". These sizes do not necessarily describe a particular dimension of the drive shape, but rather are arbitrary designations.

Modular weapon system

A modular weapon system (MWS) is a rifle which has components that can be reconfigured to give the weapon different capabilities. For example, the Stoner 63, is a 5.56×45mm NATO, modular weapon system, using a variety of modular components, it can be configured as a rifle, a carbine, a top-fed light machine gun, a belt-fed squad automatic weapon, or a vehicle mounted weapon. Modularity provides several advantages to military organizations, such as allowing units to quickly tailor weapons to meet immediate tactical needs, to quickly repair weapons, and to reduce overall logistical burdens and costs. However, it makes weapons tracking more complicated as weapons can be easily converted into different types of weapons.

Pencil sharpener

A pencil sharpener (also referred to as pencil pointer or in Ireland as a parer or topper) is a tool for sharpening a pencil's writing point by shaving away its worn surface. Pencil sharpeners may be operated manually or by an electric motor. It is common for many sharpeners to have a casing around them, which can be removed for emptying the pencil shavings debris into a trash bin.

Rößler (firearms manufacturer)

Rößler, sometimes written Roessler, is an Austrian firearms manufacturer of high-end rifles both for the hunting, sport and tactical market.

The company's Titan 3, 6, 16 and Alpha models feature a lock time of 1.6 milliseconds.

SIG Sauer 404

The SIG Sauer 404 is a lightweight bolt-action rifle manufactured by SIG Sauer. The rifle was launched in 2015, and is a direct predecessor of the SIG Sauer 202. It has a modular construction allowing for easy replacement of components and caliber changes. This 404 is currently made in a large selection of calibers and a modular barrel-change system allows changing between calibers.

While the 404 has a similar appearance to the 202 on the outside, it has several upgrades and updates, and parts are not necessarily compatible. Some differences are that the 404 has a cocking lever instead of a push button safety like on the 202. Unlike the 202, the 404 uses the same receiver for magnum and non-magnum calibers.

SIG Sauer SSG 3000

The SIG Sauer SSG 3000 (Scharfschützengewehr 3000, literally Sharpshooter Rifle 3000) is a bolt-action, magazine fed rifle chambered in 7.62×51mm NATO. It was developed in Germany. It is a common law enforcement sniper rifle in both Europe and the United States. The SSG 3000 was developed by SIG Sauer GmbH and is well renowned for its high quality.

Screw terminal

A screw terminal is a type of electrical connector where a wire is held by the tightening of a screw.

Tapestry (DHT)

Tapestry is a peer-to-peer overlay network which provides a distributed hash table, routing, and multicasting infrastructure for distributed applications. The Tapestry peer-to-peer system offers efficient, scalable, self-repairing, location-aware routing to nearby resources.


VCDS (an abbreviation for "VAG-COM Diagnostic System" and formerly known as VAG-COM) is a Microsoft Windows-based software package, developed and produced by Ross-Tech, LLC since May 2000. It is primarily used for diagnostics and adjustments of Volkswagen Group motor vehicles, including Volkswagen Passenger Cars, Audi, Bentley (limited), Lamborghini (limited), SEAT, and Škoda automobiles, along with Volkswagen Commercial Vehicles. The name "VAG-COM" derives from the acronym for Volkswagen Auto Group (VAG), the former name of the Volkswagen Group.

VCDS will perform most of the functions of the expensive electronic diagnostic tools available only to official dealers, like the current VAS 505x series diagnostic tools. In the past, these dealership-only tools have prevented owners, and many small independent repair shops from performing some fundamental tasks, such as diagnosing problems, diesel ignition timing, modification of convenience options such as automatic door unlocking, coding a replacement electronic control unit (ECU) or key to the vehicle, and monitoring of many vehicle sensors for diagnosing problems. Unlike generic on-board diagnostics (OBD-II or EOBD), VCDS uses the more in-depth Volkswagen Group-specific manufacturer protocol commands, which allows the user to access all diagnostic capable vehicle systems — even in vehicles which are not covered by generic OBD-II/EOBD (e.g. pre-1996). In general, there are two ways to use this software, either as a package (software and hardware) distributed by the manufacturer or their agents, or, by building your own interface hardware and using it with the publicly available but limited shareware version of the software.

VCDS is also capable of interfacing vehicles which use the generic OBD-II/EOBD protocols. However, the OBD-II and EOBD standards only allow for limited diagnostics, and no adjustments to any of the ECUs.

Hub, wheel, and tire
Drivetrain and bottom bracket


This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.