A 31-piece Allen key set (also called a hex key set or hex wrench set) is a toolkit of small hand tools used to drive hexagonal (6-sided) screws and bolts. These screws are extremely common in furniture, bicycles, machinery, automotive parts, electronics, and DIY projects. Chrome vanadium steel construction — durable and wear-resistant for long life Heat-treated or hardened finish for strength and to resist bending Chamfered or precisely machined tips for smooth insertion and reduced stripping Organized case or foldable holder so each key is easy to find and store Combination of short and long arms for torque and deep-set accessibility