This is a  Pass & Seymour L6-30R or L630-R locking receptacle.  It is brand new, MADE IN U.S.A. and in original factory box. Pass and Seymour is among the most respected electrical device manufacturers. This receptacle will accept L6-30P male locking plugs.  It is 3 wire and 30 amp rated for 250 volts. Leviton equivalent part number is 2620 and Hubbell part is 2620R.  NEMA configuration is L6-30R.