Milwaukee Valve Check Valve, 1 2 in, Single, Inline Swing, Bronze, FNPT x FNPT 510T 1 2 Length 30.125" The mechanism is spring actuated The mechanism is spring actuated to keep constant tension inside of the unit and continuously push the unused towels forward in the dispenser The Bobrick B 3947 Paper Towel Dispenser and Waste Receptacle is the perfect combination unit to order for restrooms where you want the convenience of a single solution for dispensing towels and disposing of waste Allows flow in one direction and helps prevent fluid backflow this MILWAUKEE VALVE swing check valve is suitable for use in plumbing and heating applications Model can be mounted vertically or horizontally to ease installation