Innovation at its best is the way to explain the function of the Sherwood First Stage Regulator. The first stage regulator incorporates Sherwood&&';;s Dry Sealed Spring. This simple yet unique design has a flow-by piston that mechanically balances the air of the first stage ensuring excellent breathing characteristics at full or low cylinder pressures. Balanced flow-by piston design, which is a fail-safe mechanism, with a patented dry seal internal mechanism to keep the intricate components clean and contaminate free no matter what kind of environment you dive it in, constructed from marine grade chrome plated brass for long life and durability. Sherwood&';s Dry Sealed Spring design Keeps intricate components clean and contaminate free Mechanically balanced flow-by piston Flow-by piston: "Fail Safe" mechanism Excellent breathing characteristics at full or low cylinder pressures Marine grade chrome plated brass for long life and durability No messy oils or grease as with more sophisticated designs Environmentally sealed without the mess Two 7/16" threaded high pressure (HP) ports Four 3/8" threaded low pressure (LP) ports Tee-shaped design: Reduces regulator profile, minimizing opportunity to contact back of head High capacity inlet filter for smooth delivery of air to second stage Nitrox Compatible: Yes, Up To 40%