This is the Ocean Reef Surface Air Valve for G. Divers Series Full Face Mask Features: Allows the diver to breathe ambient air while at the surface Can be easily assembled on the octo/SAV port Each SAV comes with 4 colored silicone rings to match the mask color FULL MANUFACTURER&';S WARRANTY The Neptune Space G.divers may be equipped with a surface air valve (SAv) that allows the diver to breathe ambient air while at the surface.