This is the Atomic Universal Comfort Swivel Hose in Brass Fits Most Second Stage Scuba Regulators Features: Fits most second stages with standard 9/16-18 hose connection Nitrox compatible to 40% (The recreational limits of Nitrox) Eliminates cumbersome binding that divers experience from their second stage, making it easier to move your head side to side, or up and down Comes with 32 regulator hose Universal Comfort Swivel Hose (fits Most Second Stages With Standard 9/16-18 Hose Connection) 32inch