Contains mm Sizes: 2, 2.5, 3, 4, 5, 6, and 8 ,EKLIND hex keys (allen wrenches) are used to drive internal hexagon socket (allen head) fasteners. These tools are made with EKLIND Alloy Steel that is heat treated, quenched and tempered for optimum strength, torque and ductility for safety and coated with a rust resistant finish.