Mounting Bushing: Nickel-plated copper alloy with knurled flange.
Insulating Spacer: Rigid plastic.
Insulator/Spring Mount: Thermoplastic.
Springs: Copper alloy.
Terminals: Tip: Copper alloy. Ring: (Number 152B only) copper alloy.
Sleeve: Steel, tin-plated.
Hardware: Supplied with one, Number P10531 nickel-plated copper alloy hex nut, and one, Number P14761 nickel-plated copper alloy flat washer.