Steel: 31CrV3 47—52 HRC Chroming H: 85 mm Length: 255 mm An Allen wrench (also known as a "hex key") is used for working with fasteners that have an internal hexagon. Angle wrenches combine two levers in their design: a longer one for applying maximum force and a shorter one for quick rotation. They are also used when working with fasteners in limited space conditions. The high strength characteristics help to avoid damaging the edges of the fasteners. You can also buy a set of hex keys.