Simmons Control Center Check Valve Silicon BronzeBronze cast body Bronze cast poppet Female threads VFD Compatible All Simmons bronze check valves are CERTIFIED LEAD FREE and include Buna N O Ring, stainless steel spring, stainless steel washer, and stainless steel locknut. All valves through 1 have a working pressure of 400 PSI, while valves 2 and larger have a working pressure of 600 PSI. Check valves rated for 190F maximum temperature. Part No. Size Weight lbs 601SB* 1 1. 3 602SB* 1 1 4 1. 7