This 3″ Sch 80 PVC Swing Check Valve, VITON, (SOC x SOC) has a disk inside the swings open and closed to prevent flow in one direction using back pressure. Socket connections are joined to pipe of the same diameter with solvent welding. Sch 80 PVC is robust and durable, perfect for commercial and industrial applications. VITON seals provide increased temperature resistance than EPDM seals and recommended for exposure to oils, gasoline and aggressive chemicals. Our prices are a fraction of what you pay at your local plumbing store, order from Petram PVC Supply for quick shipping.