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 0.5 lb spring loaded gate, allowing it to be installed in any orientation. The CR2® valve is available in 1-1/2 in slip, 2 in slip and 2-1/2 in spigot. Economy version without Hastelloy® spring available.