As a car guy, I use drive tools like ratchets, breaker bars, and torque wrenches on almost a daily basis. What makes them so useful to me is the ability to use different sockets for installing or removing fasteners, regardless of their shape and size.
The most common sockets I use, and what most people will be familiar with, are 6-point hex sockets. However, with the advent of new standards and new fastener technology, in general, other types of fasteners are becoming more and more popular. As a result, I’ve accumulated many different socket types for use in these situations.
In an effort to develop a knowledgebase, I think it would be useful to make a comprehensive list of them here. I also want to include what these sockets are used for and when. Let’s start with an oldie but a goodie – the 4-point socket.
Socket Types:
4-Point Sockets4-point, or square, sockets aren’t as common as they once were, but are still widely used today. Square head fasteners have some distinct advantages over hex shape fasteners. First, they’re cheap and easy to produce. Second, since more surface area is in contact with the part being fastened, they are more resistant to loosening when compared to standard hex shaped fasteners. Finally, the large surface area prevents rounding over of the fastener by a socket or wrench.The big downside, and probably the main reason why they’ve fallen out of favor, is that they can only be accessed at 90 degree angles. In some cases, and in tight spots, specifically, it may be impossible to get a 4-point socket or wrench on the fastener. As such, they’re are generally used in wide-open places with direct access. | |
5-Point SocketsPersonally, I’ve never used a 5-point socket or run across a 5-point fastener. From my research, 5-point, or penta sockets, are often used on 5-point fasteners found on water meters, shut off valves, electrical panels, and other utility equipment.Since they are so obscure, they offer great tamper resistance owing to the fact that (almost) no one will have a 5-point socket to open up something they shouldn’t. | |
8-Point Sockets8-point sockets, sometimes called double square sockets, are used on square fasteners. These sockets are an improvement on 4-point sockets in that they allow better access to square fasteners in confined spaces.Like 4-point sockets, 8-point sockets aren’t extremely common. Though, they are used often in some applications. | |
10-Point Sockets10-point sockets are used in the automotive industry. 10-point fasteners are typically found on flex plates and clutch pressure plates. Due to their obscurity, they’re also used as an anti-theft device on some OEM and aftermarket wheels. | |
Bi-Hex SocketsBi-hex sockets, commonly called 12-point sockets, are very common and chances are good you have a few in your collection.These sockets can be used on both 12-point bi-hex fasteners and standard 6-point hex fasteners – though, it is recommended to use a standard hex socket when possible. The additional points on these sockets make attaching it to a fastener easier in certain conditions. If you are in a tight spot or if the fastener is obscured, for example, the extra points and reduced angle can be helpful. Because not as much surface area is in contact with a fastener, however, these sockets increase the likelihood of stripping a fastener – particularly with highly torqued, rusted, or damaged fasteners. | |
Bolt Extractor SocketsSince the advent of nuts and bolts, people have been stripping them. As a result, many different bolt extractor sockets have been designed to get them off.Bolt extractor sockets are available in many different shapes and sizes and typically utilize splines or teeth that bite into the fastener. As they’re turned, the extra purchase these sockets offer is hopefully enough to get the fastener loose. Note that bolt extractor sockets will usually destroy the fastener. Though, if you need to use them, then the fastener will most likely be in poor condition and need to be replaced anyway. | |
External Torx® SocketsExternal Torx®, or E-Torx® sockets, have a unique 6-point design with a 15 degree drive angle. These sockets are made specially for use on external Torx® fasteners.E-Torx® fasteners are designed to overcome some shortcomings of hex fasteners. For one, the drive angle provides increased torque transfer and reduced radial forces. This protects against camout in high torque situation, and, by extension, prolongs the life of the fastener and socket. These fasteners are widely used in automotive and mechanical applications for securing parts like seatbelts, suspension components, and engine covers. As such, a good set of external Torx® sockets deserves a spot in any mechanic’s toolbox. | |
Flex SocketsMost sockets are rigid by design. There are places, however, like near obstacles, where it can be difficult to access a fastener with a traditional socket. Enter flex sockets.These sockets are made with one or more mechanical joints that let them attach to fasteners at extreme angles. While standard hex and bi-hex shapes are most common, these sockets are available in a myriad of types. In addition, flex socket extensions are available that accept any socket that uses a standard drive size. | |
Hex SocketsHex fasteners are standard for many applications ranging from automobiles to children’s toys. As such, hex sockets are among the most popular, and useful, types of socket.These sockets, commonly called 6-point sockets, feature 6-points with a 120 degree drive angles. A significant improvement on 4-point sockets, hex sockets can attach to fasteners at a 60 degree angle instead of 90. As I mentioned before, a 12-point bi-hex socket can be used on a hex fastener, but a hex socket really is the preferred tool. This is because they offer more contact with the head of the fastener so more force can be applied without potentially stripping it. | |
Hex Bit SocketsA hex bit socket, also called an Allen bit socket, is designed to be used with fasteners with an internal hex drive. These sockets come in various sizes to fit different size fasteners.Hex bit sockets can be used anywhere an Allen Wrench can. As such, they’re useful for anything from working on cars to building Ikea furniture. | |
Impact SocketsImpact sockets are made from thicker, softer steel and are designed specifically for use with impact wrenches. These types of sockets withstand high torque and sudden impact better than standard chrome sockets, which may break, or even explode, in these conditions.This makes them ideal for installing or removing fasteners in tough applications, such as working on automobiles or heavy machinery. Most socket types are also available in impact socket versions. | |
Insulated SocketsInsulated sockets have a layer of insulation material, such as rubber or plastic, covering the metal body of the socket. The insulation provides a protective barrier between the electrical current and the user, reducing the risk of electric shock or injury.Insulated sockets are commonly used in electrical applications, such as working with live wires or in other high-voltage environments, where there is a greater risk of electrical contact. Insulated sockets are often color-coded to help users easily identify the correct size and type of socket for the job. Like impact sockets, insulated sockets are available in a myriad of shapes and sizes. However, since they are a specialized tool, there may not be as wide of a variety in some cases. | |
Oil Filter SocketsOil filter sockets are designed specifically to remove and install oil filters. Oil filter sockets are typically made of metal and have a cup-like shape with special grooves or flutes that allow them to securely grip the oil filter.Oil filter sockets come in a variety of sizes and styles to fit different makes and models of vehicles, and they are commonly used in automotive maintenance and repair to make oil changes easier and more efficient. | |
Pass-Through SocketsPass-through sockets, also known as through sockets, are a type of socket that has a hole in the center of the socket. This design allows the socket to fit over a long bolt or stud, which can pass all the way through the socket and protrude out the other side.Pass-through sockets are typically used in applications where long bolts or threaded rods need to be tightened or loosened, and a traditional socket or wrench cannot be used due to the length of the fastener. Pass-through sockets often come in sets with a matching pass-through ratchet that can be used with various size sockets for increased versatility. | |
Spark Plug SocketsSpark plug sockets are designed specifically for removing and installing spark plugs in engines. Spark plug sockets are typically deep sockets with a rubber or magnetic insert that helps to grip and protect the ceramic insulator on the spark plug.The insert also helps to prevent the spark plug from falling out of the socket during use. Spark plug sockets come in a variety of sizes to fit different spark plug configurations, and they are often used in automotive maintenance and repair to replace worn or fouled spark plugs. | |
Torx® Bit SocketsTorx® bit sockets are designed to fit internal Torx® fasteners. Torx® bit sockets are commonly used in automotive and mechanical applications where Torx® screws are used to secure components, such as in brake systems, engines, and transmissions.Torx® bit sockets come in a variety of sizes to fit different Torx® screw sizes. | |
Torx Plus® Bit SocketsTorx Plus® sockets are designed to fit Torx Plus®, or star plus, fasteners. The Torx Plus® system is an improved version of the original Torx® system, with a different geometry that provides a greater contact area between the driver and the screw head. This design allows Torx Plus® screws to handle higher torque and reduces the risk of cam-out, which is when the driver slips out of the screw head during use.Torx Plus® sockets have a similar shape to standard Torx® bit sockets, but with different internal geometry to fit Torx Plus® screws. Torx Plus® sockets come in a range of sizes and are commonly used in high-torque applications, such as in the aerospace and automotive industries. While standard Torx® bit sockets will fit Torx Plus® fasteners, Torx Plus® bit sockets will not fit standard Torx® fasteners. Mismatching the two, however, may result in damage to the bit or fastener because of the difference in shape and geometry. | |
Triple Square SocketsTriple square sockets, also called spline sockets, are specifically made to fit triple square fasteners. These fasteners feature 12 evenly spaced points and designed to prevent camming out and provide better torque control when compared to a standard hex or slotted fasteners.These sockets are commonly used in automotive applications – especially in European vehicles, which often use triple square fasteners in various parts of the engine and transmission. They are also used in industrial and construction settings. Triple square sockets come in various sizes to fit different fasteners, and they can be used with a ratchet or breaker bar to provide additional torque for tightening or loosening. It’s important to use the correct size and type of socket for a specific application to ensure safe and effective work. | |
Universal SocketsUniversal sockets are designed to fit a wide range of fasteners, including ones of different size and shape. They are typically adjustable and can fit both metric and standard fasteners.Universal sockets typically have a unique design that allows them to grip a fastener on the outside instead of the corners or edges, which is the traditional approach used by standard sockets. This design helps to distribute the pressure more evenly around the fastener, reducing the risk of damage and rounding of the corners or edges. Universal sockets are particularly useful for DIY enthusiasts and mechanics who work on a variety of projects and need to switch between different sizes and shapes of fasteners frequently. They can help reduce the number of sockets needed, saving time and space in a toolbox. It should be noted, however, that universal sockets sometimes don’t work as intended and are generally not as efficient or safe as using the proper socket for the application. | |
Wheel Lug SocketsWheel lug sockets are used to install or remove lug nuts without damaging the wheel or lug nut, itself. They are essentially thin walled impact sockets with a plastic or rubber sheathing to prevent abrasion.Wheel lug sockets are commonly used by automotive technicians and DIY car enthusiasts to remove and replace wheels for maintenance or repair. They can come in a variety of shapes and sizes, depending on the lug nut configuration. |
What You Should Know About Socket Size And Safety
I didn’t talk much about socket size above, but it is an important consideration when working with sockets, as using the incorrect size or type can result in damage to the fastener or the socket, and can even cause injury to the person working with the tool.
Socket size refers to the width of the socket opening or diameter of the bit, and are usually measured in metric units (typically millimeters (mm)) or imperial units (typically inches (in)). There are many different socket sizes available, with the most common sizes ranging from 4mm to 24mm (metric) and 1/4 inch to 1-1/2 inches (imperial).
The most common socket drive sizes used in automotive and mechanical applications are 1/4 inch, 3/8 inch, and 1/2 inch. 1/4 inch sockets are the smallest, and are typically used for smaller, lighter-duty fasteners, such as those found in electronics and appliances. 3/8 inch sockets are a popular choice for automotive applications, and are also commonly used in household repairs and maintenance. 1/2 inch sockets are the largest of the three, and are typically used for heavy-duty applications such as working on trucks and heavy machinery.
In addition to these common sizes, there are also larger and smaller drive sizes available, including 3/4 inch, 1 inch, and 1-1/2 inches for heavy-duty applications. Some socket sets come with a wide range of socket sizes, allowing users to tackle a variety of different fasteners with ease. It’s important to choose the right socket size for the job, as using a socket that is too small or too large can result in damage to the fastener, the socket, or the tool being used.
If I’ve missed any socket types or want to add anything, leave it in the comments below. And, if you’re interested in learning more about ratchets and sockets, check out our Ratchets And Sockets Category.
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