Chromate plated, case-hardened steel ensures this G-style plug can better resist rust. With a standard cubic feet per minute air flow of 99, and a 1/2 inch basic flow size, the female national pipe thread plug measures 1/2 inch. These G-style couplers can work with industrial interchange plugs, G-style plugs of G-style Parker/TruFlate plugs. For a better seal, these female plugs have eight locking balls.