Range power outlet. Accepts aluminum or copper conductors. Designed to be installed in 2-gang electrical boxes without mud rings. Maximum 4 AWG (American Wire Gauge). 3-pole, 3-wire, non-grounding. 2.15 inch diameter. Black, 50 amps/125 volts/250 volts. NEMA (National Electrical Manufacturer's Association) 10-50R, UL (Underwriter's Laboratories) listed.