The Hayward ECX4077B1 Check Valve is an essential component for optimal flow management in pool and spa filtration systems. This check valve, made of robust plastic and metal, prevents backflow, which could interrupt system operation and harm water quality. The check valve allows water flow in just one way, preventing reverse flow that could contaminate or harm the filtration system. ... https://www.usapoolshop.com/ecx4077b1-hayward-check-valve