Steel: 6140CrV 44-48 HRC Nickel-plating A: 11 mm B: 11.5 mm Length: 180 mm The double-sided hinge key is a non-detachable version of a drive and extender with a hinged twelve-sided end head (180° angle). It is designed for efficient use and transmission of significant force when working in hard-to-reach places. Rotating the end head parallel to the body of the key allows for quick loosening and tightening of fasteners when no significant force is required. You can also purchase a set of hinge keys.