How to Choose Socket Adapter and Extension Set

You may think you’re strong with a wrench, but a socket wrench can twist the head of a bolt right off. The ratcheting wrench makes tightening and removing bolts incredibly easy. Know your ratchets, sockets, and accessories.

A socket wrench is most commonly a handle with a 90 degree ratchet, along with a set of cylinder shaped “sockets” of various sizes. The sockets fit onto the ratchet by way of a square nub. You can set the ratchet to either tighten or loosen, then keep the socket in place on the nut while you turn the handle. It’s that simple.

What is a ratchet?

A ratchet is a type of gear mechanism that holds when going one direction, and releases when going the other direction. A socket wrench isn’t the only type of ratchet. You can also get ratcheting screwdrivers (which can help minimize wear on screw heads) and T-handled ratchets (for a middle ground of torque between a screwdriver handle and a wrench handle). You can also get a personal valet to bathe you and butter your toast, but for now, let’s avoid any frivolous purchases for now: the socket wrench should be the only ratcheting tool you’ll really need.

Socket wrench sets also come in either SAE or Metric sizes. Fortunately, here in the US, the ratchet handle is standardized to fit both. The square nub is typically 1/2”. Small ratchets use a 1/4” nub (and most sets come with an adapter that goes from 1/2” to 1/4” for the smaller jobs). An extra large ratchet uses a 3/4” nub, but these are very rare, unless you work on airplanes or live on the planet Hoth.

Basic design of a simple ratchet.Animation by ZabMilenko

Most socket sets also come with a couple of extenders, that help you get your wrench into deep places, like spark plugs in an engine block.

The Spark Plug Wrench

When you hear the term “spark plug wrench” you should visualize a type of socket. The spark plug socket is a longer cylinder, designed to fit a spark plug. On most cars, you will need either a 5/8” or 13/16”, but check for yourself or read your car’s manual before spending money.


The same essential techniques and pitfalls for any wrench apply to the socket wrench: use the right size. Do keep in mind that a ratchet can be very powerful — and by design it holds in place better than other wrenches. It’s possible to twist the head right off of some bolts. As previously mentioned, if the nut or bolt is super tight, lube it up with some Liquid Wrench or silicone spray.



  • Attaches to a ratchet to tighten and loosens nuts and bolts
  • Also works with torque wrenches and breaker bars
  • Available in standard (SAE) and metric sizes — some are color-coded help you quickly distinguish between the two types
  • Fits either a 1/4-inch1/2-inch or 3/4-inchratchet — smaller sizes fit smaller fasteners while larger fasteners usually need sockets with larger drive sizes
  • Shallow, low-profile sockets (left image) fit spaces where there is little clearance above the head of the fastener.
  • Deep sockets (right image) can reach the nut on a longer, threaded bolt. They also allow you to reach recessed fasteners
  • 6-point sockets (left image) and 12-point sockets (right image) are available to fit a variety of fastener heads. Universal socketswork with more even fastener types, including spline, star and square
  • Flex or flexible sockets have a built-in joint that allows you to use the handle at different angles, a useful feature in tight spaces

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