Steel: 31CrV3 47-52 HRC Chrome plating H: 50 mm Length: 175 mm The inch hex key (also known as an "Allen wrench") is used to work with fasteners that have an internal hexagon. Angle keys have two levers in their design: elongated for applying maximum force and short for quick rotation, and are also used when working with fasteners in limited space conditions. High strength characteristics help prevent damage to the edges of the fastener.