What is a Socket & What Are They Used For?

What is a Socket & What Are They Used For?

Sockets are very common tools and can be found in most toolboxes. But what exactly is a socket and what are they used for? 

What is a Socket?

socket is a tool that attaches on to the end of a ratchet, or socket wrench, with the purpose of tightening or loosening a fastener by turning it.


How Does a Socket Work?

Sockets work in conjunction with ratchets. The socket snaps on to one end of the ratchet thanks to a square-drive connector. The other end of the socket is then fitted over a fastener. The ratchet allows the socket to engage with and tighten the fastener when it is turned in a clockwise direction and loosen the fastener when it is turned in an anti-clockwise direction.


How to Identify a Socket?

Sockets are generally internally square-shaped at one end. This end is called the square-drive connector. It is used to connect a socket to a ratchet. It is also the end that is being driven or turned by the ratchet.

The other end of the socket is called the head end. This end can be a number of different shapes depending on the size and type of fastener that the socket is designed for.


How to know what Fasteners a Socket can be used on

The shape and size of a socket will determine what type of fastener it can be used to adjust. There is a type of socket that corresponds to every different type of fastener.

For example, hex and bi-hex sockets are designed to turn six-sided fasteners, whilst bolt grip sockets are designed to remove damaged fasteners rather than to tighten fasteners.


Socket Drive Sizes

Sockets most commonly have five different drive sizes: ¼”,⅜”, ½”, ¾” and 1”. These drive sizes correspond to the drive that is required on the ratchet tool. Usually, the larger the size of the socket means the larger the drive size that is required. This is due to the forces that will be applied to the socket and ratchet tool. However, an adapter can be used to allow sockets or ratchet tools with different drive sizes to be used together. For example, a ½” drive tool can be used with a ⅜” thanks to an adapter.


Types of Sockets

There are a variety of different types of sockets that all differ depending on the type of ratchet that they are designed to be used with or the type fastener they are designed to be used on. There are also socket sets, which can offer a range of sockets in different drive sizes and fastener shapes.

Hex Sockets

Hex Socket 

Hex sockets are some of the most common types of socket. They can be found as two main types – the hex 6 point and the bi-hex 12 point. Hex sockets feature a square-drive connector at one end, which is used to attach them to a ratchet, and a hexagonal or bi-hexagonal recessed head at the other end, which is used to turn fasteners, such as nuts and bolts.


Socket Bits

Socket Bits

Socket bits are a combination of a screwdriver bit and a hex socket. They still connect to a ratchet using a square-drive connector as a hex socket would, but the other end of the socket bit fits into the corresponding shaped female recess on a fastener head. They either have a Phillips screwdriver head, a flat-headed screwdriver head, a Pozidriv screwdriver head, a Torx screwdriver head, a hex screwdriver head or a multipoint/spline screwdriver head.

There are two main types of socket bits, one-piece and two-piece. One-piece socket bits have a screwdriver bit fixed to the opposite end of the square-drive connector, or they are moulded into the shape of a driver bit. Two-piece socket bits have a socket body and a removable screwdriver bit that will be held in place by a screw. Both types come in various shapes and sizes depending on the features of the fastener head.


Pass Through Sockets

Pass Through Socket

Pass through sockets are slightly different to other sockets in that they don’t have a square-drive connector. This is because they are designed to be turned by a ratchet that fits over the top of the socket. Consequently, these types of sockets are hollow, which allows for long fasteners to pass all the way though. They are perfect for tightening or loosening nuts on very long bolts that even a deep socket is unable to reach.


Spline Sockets

Spline Socket

Spline sockets are designed to tighten and loosen spline fasteners; however, they are also ideal for use on hex and bi-hex fasteners, such as nuts and bolts. This makes them a useful socket to use across different types of fasteners. This type of socket delivers up to twice the amount of torque on spline fasteners that would be applied to a bi-hex fasteners from a bi-hex socket.


Impact Sockets

Impact Socket

Impact sockets are designed to work with pneumatic or cordless impact wrenches and are usually made from chrome molybdenum, which is able to cope with a continuous impact action without breaking. Typically, this type of socket has thicker walls than a standard socket and features a locking pin to ensure the it doesn't come off the end of an impact wrench. These sockets are predominantly used within the automotive and aerospace industry due to the robust nature of the product.


Torx Sockets

Torx Socket

Torx sockets have six points within their heads which form a star-like shape. They are specially designed to fit torx screws and are available in a wide variety of sizes. Torx sockets are designed to apply the correct level of torque without slipping. Because of this, they are perfect for heavy-duty applications.


Insulated Sockets

Insulated Socket

Insulated sockets get their name from the insulated coating they have which protects them from an electrical current. They can be used with a live working current for both an AC and DC electrical current. Insulated sockets must be used with their corresponding insulated ratchet.


Spark Plug Sockets

Spark Plug Socket

Spark plug sockets have the purpose of fitting or removing spark plugs from engines, as their name suggests. Spark plug sockets often have rubber inserts that sit in the inner part of the socket, which aids to hold the spark plug and prevent it being damaged by the socket. They come in a variety of sizes depending on the size of the spark plug.


Adjustable Multi Sockets

Adjustable Multi Socket

Adjustable multi sockets feature jaws that are able to adjust to fit different sizes of fasteners. This means that many different sized fasteners can be adjusted using the same socket. These types of socket prevent the rounding of corners on fasteners, as they distribute an equal force which is applied on all sides of the fastener. Adjustable multi sockets are adjusted by turning the outer part of the socket which moves the jaws of the socket. These jaws then clamp around the head of a fastener.


Universal Sockets

Universal Socket

Universal sockets feature lots of spring-loaded pins within the actual socket head. When the socket is placed over the head of a fastener, the spring-loaded pins that come into contact with the fastener withdraw. This leaves the remaining pins perfectly surrounding the fastener head, allowing the socket to fit a variety of different sizes and designs of fastener. Because of this, universal sockets are often perfect for use when trying to adjust a damaged fastener.


Oil Filter Sockets

Oil Filter Socket

Oil filter sockets are large and shallow. They are designed to fit and remove oil filters from vehicles, as their name suggests. Often the walls of these sockets are much thinner than on other sockets. This is due to the fact that they don’t need to withstand high torque forces due to oil filters having plastic thread that prevents them from being over-tightened.


Bolt Grip Sockets

Bolt Grip Socket

Bolt grip sockets are designed to remove damaged fasteners rather than to tighten fasteners. The internal walls of bolt grip sockets have a concave spiral design which allows it to fit a lot of different types of fastener heads. The edges of this design dig into the damaged fastener head, which gives it a tight grip and allows the user to easily remove the damaged fastener.


Socket Accessories

There are many different types of socket accessories available. You can use multiple types of accessories with sockets, including extension bars, breaker bars, universal joints and speeders.

Extension Bars

Extension bars are used to extend the reach of a tool and come in a range of lengths dependent on your needs.

Extension Bar


Breaker Bars

Breaker bars are used to increase the force you can apply.

Breaker Bar


Universal Joints

Universal joints are used to reach a fastener in a difficult or tight position, whilst still allowing movement and the use of the socket.

Universal Joint



Speeders are used to allow the user to quickly tighten or loosen a fastener using a rotation of the handle.



Heamar sell a variety of individual sockets and socket sets with drive sizes including ¼”,⅜”, ½”, ¾” and 1”. 

We also offer socket accessories including socket extension bars and adaptors.

Why not check out our other tool guides?

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