Profile: The O-Ring Store specializes in supplying o-rings and o-ring kits to a large variety of customers. We have o-rings and basic seals in single to bulk in a variety of sizes & elastomers including nitrile, viton, silicone, EPDM, NSF, FDA and teflon o-rings. Our standard 70 durometer nitrile o-ring kit contains a total of 382 o-rings, in 30 of the most often used AS568 standard sizes. National o-ring gauge identifies o-ring dash size by ingeniously converting the inside diameter and cross section to corresponding AS568 dash sizes. Sizing cone and tape measures dash sized AS568 o-ring at a glance. The tape included is designed to measure the large inside diameter and it works using same principle as the PI tapes. The OR-38 filter o-ring can be used with 3/8" inlet/outlet housings with a 3.5" diameter housing sump. The OR-38 rubber o-ring is 3.5" in diameter and is an FDA Buna-N o-ring.