Hexagon Keys are also known by many other names including Hex Keys, Hex Wrenches, Allen Keys, and Allen Wrenches, Torx Wrenches, Ball-End Wrenches, are wrenches for tightening or loosening socket head screws. The tool is usually formed of a single piece of hexagonal rod of hard steel, with blunt ends that are meant to fit securely into the screw's socket Head. Bent in an "L" shape with unequal arms, the tool is usually held and twisted by the long arm, creating a large torque at the tip of the short arm.
are available on the FCH Network with Imperial/US diameters that range from #1 to 6 and with Metric diameters that range from M2 to M42. The length of is usually measured from the point to the underside of the head.