Heavy gauge brass line contacts. High impact and chemical-resistant nylon face. Automatic grounding system. Terminal sizes number 14 - 10 AWG. Voltage ratings permanently marked on device. Materials face and base are nylon, strap is 0.05" thick steel, zinc plated, auto ground clip is bronze wire. Line contacts are 0.037" triple-wipe brass, terminal screws are number 8-32 steel, ground screw is number 8-32 steel (green). Screw terminal guards are PVC. Listed to UL 498, UL verified to Federal Spec. WC-596G, CSA Certified to C22.2, no. 42. Flammability meets UL 94 requirements; V2.temperature rating: -4 to 158 degrees F. Dielectric voltage: withstands 2000 volts per UL 498.