FASTENERS & TOOLS | For Threaded Rigid Conduit and Imc | Grounding, Metal Box | Hex-Key Ends Are Square-Cut for a Secure Full-Depth Fit and Maximum Contact With the Hex Socket to Prevent Slippage and Stripping of the Socket | Provides a Hardened Bearing Surface, Creating More Uniform Torque Control and Load Distribution | Use With 11-in-1 and 10-in-1 Screwdriver/nut Drivers