Used Atomic Aquatics M1 Regulator Din SealedM1 Sealed Features Factory ready for Nitrox to 50% or oxygen mixes to 80% when special guidelines are followed First stage materials are chrome plated Brass for the body and Monel for key internal components Atomic Jet Seat high flow piston first stage Freeze protected factory sealed first stage also prevents contamination such as silt and sand First stage ports: 2 HP fixed 5 LP on swivel cap