HFS (R) Sanitary Check Valve - One Way Flow - Tri Clamp Clover Stainless Steel (1.5IN) This one-way check valve allows flow in only one direction. When flow stops the valve automatically closes to stop materials from back-flowing. The pressure required to open the valve and be adjust by swapping out the inner spring (only one spring included) or rotating the spring plate. Fits Tri-Clamp: 1.5" Material: SAE 304 Stainless Steel - Quickly comes apart for easy cleaning. Adjustable pressure via spring replacement (1 spring included)