... design value 0.6-0.9MPa) Structure:mainly by whole vision mask, demand valve, pressure reducer,warning whistle,pressure gauge ... Mask(ISI):Conform to Asian people face, spherical surface window, vision is specially wide, the comunication clear, sealing material soft, ... pressure gauge has the functions of anti-impact, waterproof and night display. The alarm whistle loud.Backboard uses high strength nylon ...