Our PSSV Series, Self-sealing Check Valves,  are made from either Polycarbonate or Polypropylene with Barb connector sizes of 3/16 inch or 5/16 inch. Product is made in a class 8 clean-room. The seal is a retractable silicone disk that prevents backflow in a number of air and liquid applications making it an ideal option for the Medical Industry. Open pressure is approximately .20 PSI