The CP-04 is a glass-filled polypropylene aerial check valve with 1/8″ threaded female inlets and outlets. Using a patented needle/seat design, it provides instant shut-off. The stainless needle seats into an O-ring in a stainless core, with a Viton diaphragm protected by a Teflon diaphragm on the needle. Flow capacity is 5.2 GPM at 40 psi, with springs beginning to open at approximately 12 psi.