Swiss knife with allen keys. 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 available in a Swiss knife type case that allows folding for storing the keys, as well as for easier finding of the required size for the work.