Magic Plastics 0823-20C Check Valve, Magic Plastics Smart Check, 2"Union, 1/2 lb, WaCalifornia Residents WARNING: This product can expose you to chemicals including Vinyl Chloride, which is known to the State of California to cause cancer P65Warnings.ca.gov The "Smart" Check is equipped with a 1/2” lb spring-loaded gate mechanism, allowing the valve to be installed in virtually any orientation.