Switches meet all UL 20 requirements. Grounding terminal screw standard. Combination switch with additional switch has 120/277 volt rating, ideal for fluorescent lighting fixtures typical in commercial applications. 0.050" thick steel mounting strap zinc-plated for corrosion resistance. Break-off provision for wiring both devices on same circuit or on separate circuits. Terminal screws backed out and ready for wiring. Side wire terminals accept up to #10 solid or stranded wire. Combination slot/Phillips head mounting and terminal screws ease installation with power screwdrivers. U.L. Listed.