Sizes range 3/4" X 1/2" through 4". Recommended for a maximum working pressure of 125 psi (1/2"-1"), 100 psi (1 1/4"-2") and 75 psi (3"-4"). 1/2" couplers and adapters will interchange with 3/4" couplers and adapters. Only the threads and barbs are 1/2". 1 1/4" couplers and adapters will interchange with 1 1/2" couplers and adapters. Only the threads and barbs are 1 1/4". Polypropylene cam and groove should not be mixed with aluminum fittings. Supplied with EPDM gaskets, 304 stainless steel handles and pins. Couplers and Adapters are manufactured from a glass-filled polypropylene.