GMCO Heavy Duty 3” x 4” Couplings are a one piece welded design and provide a permanent end connection to industrial rubber hoses for use in the toughest oil field applications. 3” hose size with an integrated 4” male NPT Thread allow for use in special applications that the oil field demands. Constructed of pipe grade schedule 40 API 5L Grade B Carbon Steel and Tubing and are zinc plated chromate finished to provide years of trouble free service. Couplings can be crimped or swaged for ease of installation.