Quick Connect Set, Hose to Hose, Brass, QDB21 QDB22, Fuel Gas Oxygen ORS NASCO and 347 stainless steels Controlled ferrite and 347 stainless steels Controlled ferrite in the weld deposit gives excellent notch toughness at cryogenic temperatures Deposits a max of 4% carbon in the weld metal to minimize the formation of chromium carbides and consequent susceptibility to intergranular corrosion Used on food and pharmaceutical equipment Long life with no bounce Brass construction provides long service life Non interchangeable oxygen and fuel gas connectors Instant closure on reverse flow check valves Spring loaded locking mechanism responds to fingertip action and achieves a gas tight connection Double seal socket connection on second seal