Allen key in L-Shaped shape with a tip size of 5.5. A hex key is ideal for any type of use by any professional mechanic, plumber, carpenter, electrician, as well as for household use. Hex keys are formed from a single piece of hexagonal rod made of hardened steel with chamfered ends that fit comfortably into similarly shaped screw sockets. It is bent at 90 degrees, forming two unequal length arms that resemble the Latin letter "L".