Antifreeze Drain Valve extended details protects irrigation systems that are subject to freeze damage by automatically opening and allowing water to drain when system is shut off. Valve opens to allow system to drain at low pressure (8-10 PSI) and has check valve to prevent muddy backflow water from entering system. Large diameter ribbed area allows for hand installation. Special fiber outlet allows efficient drainage while keeping debris and roots from fouling valve., B&K offers many decorative selections along with supporting pieces to complete any plumbing project.