Super-Pro® SP0801-20H2 2" S CPVC Corrosion Resistant Check Valve. The “CR2®” Back-Flow prevention check valve is completely corrosion resistant, making it the ultimate solution for protecting your expensive Heat Exchangers from the potential damage of inline Chlorinators while also maintaining a Full-Flow circulation system. Numerous features are included with the “CR2®” Valve including a proprietary designed Hastelloy® Spring, Glass-Filled Noryl injection molded shaft, 100% Silicone Gasket and a Clear, serviceable lid. The “CR2®” Valve is also equipped with a ½ lb. spring-loaded gate, allowing it to be installed in any orientation. The “CR2®” valve is available in 1½˝ Slip, 2˝ Slip and 2½˝ Spigot. Economy version without Hastelloy® Spring available.