These -4 Braided flex-hoses with 1/4 NPT ((pipe threads) Female on both ends.) stainless-steel braided Teflon flex-hoses are cleaned for oxygen system applications. They are rated for 3000 source (12,000 burst) psi service and are ideal for applications that require a remote fill-port. Hose assemblies are cleaned for oxygen service per specification (SAE) AIR1176-A. 18 inches to 8 foot lengths available. Special orders accepted for custom length applications. Expect 3 weeks for custom orders.