... the tube in which it fits) 1/8", 3/16", 1/4", 5/16" and 3/8".2.Three housing materials. nylon type ... Four diaphragm materials. fluorosilicone, Viton, silicone and EPDMFunction:1.Prevents damage to equipment, pumps, and flow systems by preventing backflow2.Tubing ... firmly.Packingplastic bag and wrapped, cased in small carton 1/8" PA66 VITON/plastic check valves/fuel valves/windshield repair equipment