The Allen Key Set is small handheld and manually operated tools used for the installation or removal of these special fasteners. Also known as a hex key, an Allen key is an L-shaped tool thats used for the installation and removal of fasteners with a hexagonal head. They consist of a single piece of material, typically metal, thats formed into a right angle. Both ends of an Allen key are hexagonal. Therefore, you can use either end to install or remove a fastener, assuming it fits. Allen Key Set is very useful.