1" Accu-Clamp™ Collar One-Piece Type, Steel, Hardened & GroundSolid working face available machineable or hardened and ground Integral clamp provides high strength, non marring hold 1117 Steel for easy machineability Accu Clamp Collars combine a non marring clamp with a solid working face that is either fully machineable or hardened and ground. The machineable Accu Clamp Collar can be used as is, or modified by drilling, tapping, threading, turning, knurling, etc. The hardened and ground Accu Clamp Collar