Steel: 31CrV3 47-52 HRC Chrome-plating H: 60 mm Length: 195 mm An allen wrench (also called a "hex key") is used for working with fasteners that have an internal hexagon. Angle wrenches have two levers in their construction: an elongated one for applying maximum force and a short one for quick rotation. They are also used for working with fasteners in limited space conditions. High strength characteristics help prevent damage to the edges of the fasteners. You can also buy a set of hex keys.