Steel: 31CrV3 47-52 HRC Chromizing H: 30 mm Length: 115 mm The hex key (also known as an "Allen wrench") is used for working with fasteners that have an internal hexagon. Angled keys have two levers in their construction: an elongated one for applying maximum force and a short one for quick rotation. They are also used when working with fasteners in tight spaces. The high strength characteristics prevent damage to the edges of the fasteners. You can also purchase a hex key set.