Hex Wrench Set Buyer's Guide

The hex wrench, also called an Allen wrench or hex key, is a specialized tool for manipulating a certain kind of bolt.

What Is a Hex Wrench?

The tool is called a "hex wrench" because it has a simple hexagonal shape. Traditional wrenches have vise structures used to grip a bolt from the side, or to cover it in the case of a socket wrench. The hex wrench works differently. It fits into a concavity in the nut, bolt or screw, and hex wrenches comes in a variety of sizes to fit different hardware. Generally, they are sold together in a progressive set.

How to Use a Hex Wrench

The hex wrench fits into a hexagonal space in the middle of a bolt head. Insert the hex wrench and turn clockwise or counterclockwise as necessary. It can be hard to get a grip with a hex wrench, because they are often small and lack a conventional handle. Also be careful not to put excessive pressure on the hex wrench or bend it the wrong way. Cheaper hex wrenches can bend easily.

Hex Wrench Sizes

Hex wrenches are made in an "L" shape, and they can be utilized using either the long or short side of the tool. They're ideal for small bolts and generally range in size from 2 to 10 millimeters or 1/32-inch to 5/16-inch.

They offer high torque for tightening and loosening and the multiple sides provide a good grip in the hole so there's rarely any slippage from the wrench. Hex wrenches should be made of first-cast steel for maximum strength.

Hex Wrench Sets

When you buy a dedicated set of hex wrenches, you'll find a number of options available. A set can be made up of loose wrenches which give you the option of using both long and short sides, meaning you can use the wrenches in more situations. This can be useful when working on engines, for instance.

• Jackey hex wrench set. A "jackey" hex wrench set is usually a set of 12 or more wrenches set into a case with a central point. This style looks a lot like a foldout Swiss army knife. The pros of this set are that you will not lose any of the wrenches and they are all in one place. The cons are they are usually short and straight and connected together, so you don't have the opportunity to use them at angles. Also, it's much harder to keep a good grip on them. The average price of the wrench set is $50.
• Ring hex wrench set. A hex wrench set on a ring is a 12-piece set that is attached to a keyring. This set is fine as long as you get one that has the ability to remove individual wrenches from the ring. If not, this set has the same limitation as the jackey set. You are unlikely to lose individual wrenches but, once again, each individual wrench has its own limitations. Hex wrenches on a key ring retain the "L" shape but unless you can remove each wrench from the ring, you can only use the short side of the wrench. You can but a ring hex wrench set for about $20.
• Loose hex wrench set. This is usually a set of 24 pieces and has each wrench piece separated. The sets that offer the very best value will range from 1/32 inch all the way up to 5/16 inch. Ideally, look for a multi-angled set, with the tip on the long end being a high-strength ball tip. They need to be made to high tolerances, and for real strength should be made of alloy steel that's been heat treated. A set like this will be able to handle all jobs involving a hex wrench. This set costs about $100.