Plated steel and stainless supplied with Silicon Bronze bolt and nut.
Electrical current running through the cable induces a magnetic field around the cable. The Everdur bolt and nut (Non-magnetic silicon bronze) used to fasten the two clamp halves together break up the magnetic field at the cable clamp location.
Assembly consists of thermoplastic elastomer cushion with plated or stainless steel clamp.
Everdur is a tradename for non-magnetic silicon bronze.