bio-regulator has double diaphragm system for prevention from water leak and corrosion of the other parts.
Also, the regulators keep their function in the cold water, because those diaphragms protect freezing the parts.

O-rings for the area of high-pressure air are used by Viton®.
Viton® fluorine elastomer is the most specified fluorine elastomer, well known for its excellent (400°F/200°C) heat resistance.
Viton® fluorine elastomer is adapted for the Nitrox diving.
※ Viton® is a registered trademark of DUPONT.