With one exception, all the diaphragm regulators we sell are environmentally sealed, including the DGX Gears D6, Dive Rite XT1, Mares 28XR, and Apeks XTX series (DS4, TEK3, DST, FSR) first stages. The Poseidon Xstream is a unique balanced rolling diaphragm ball valve design that is not environmentally sealed because it relies upon a built in thermo-dynamic anti-freeze system to remain ice free.

Piston regulators are not typically described as environmentally sealed in the conventional sense because the internals are protected by other methods inherent in their design. The DGX Gears XTRA & FIRST, Dive Rite RG5400, and Mares R2XR are piston first stages.

The need for sealing a first stage is not relevant to most types of diving, for more information read our TekTip titled Environmentally Sealing SCUBA Regulators.