Model 88-5FBHFR(R) high-flow regulator-type flashback arrestor for use with oxygen prevents the reverse flow of gases with a built-in check valve. It extinguishes flashback fire with stainless steel sintered elements. The thermal shut-off completely shuts-off the gas in case of hose fire burn-back or repeated flashbacks. Constructed of durable brass and stainless steel for extended use. They are equipped with 9/16" -18 "B" connections.