Why Stainless Steel & Titanium? Stainless Steel delivers virtually the same corrosion resistance as Titanium at a lower price. Stainless Steel does not require protective chrome or nickel plating processes that can be harmful to the environment and is 100% recyclable. The ST1 second stage features all-Titanium components as in the T2 and B2 models. A Breath of Fresh Air Environmentally conscious topside...natural breathing at depth The ST1 is another industry first from Atomic Aquatics. The first stage is beautifully machined from a special grade 316 Stainless Steel that is twice the strength of brass with corrosion-resistance approaching Titanium. The use of Stainless Steel means we are doing our part for clean air when divers are out of the water. The legendary Atomic design means divers also breathe easy at depth. First Stage: First stage machined from solid 316 Stainless Steel Atomic Jet Seat high-flow piston first stage Freeze protected factory-sealed first stage also prevents contamination such as silt and sand Nitrox ready for mixtures up to 40% First stage ports: 2 HP fixed / 5 LP on swivel cap Second Stage: All-Titanium second stage construction same as Atomic T2 and B2 models Patented Atomic Seat Saving Orifice (Titanium) Patented Atomic Automatic Flow Control (AFC) Rapid adjustment knob for manual second stage de-tuning in special situations All-stainless steel Atomic Comfort Swivel standard A new high-flow second stage case lowers breathing effort at any depth from shallow water to beyond the limits Dual material second stage cover enables entire front to be used for purge Dual silicone comfort fit mouthpiece with