Cooper 1252 Surface Mount 250V 50A NEMA 6-50R Receptacle features heavy gauge steel mounting strap zinc-plated for corrosion resistance. For use with copper or aluminum wire, 75°C rated terminals. Surface outlet receptacle has patented lay-in terminals and accept up to #4 wire. Surface receptacles 3/4" and 1" concentric knockouts and adjustable cord. Clamp allows for wiring from bottom or back.