... circuit circulation system through air sac, cooling nets, orifice plate etc, for people to breathe.3. Main PerformanceProtective ... resistance;Adopt polycarbafil, hinder dust well;Adopt non-distributed orifice plate structure, evenly distribute, absorb CO2 well;Small volume ... belt4Seal9Hook for belt5Part of ahead lock catch10Name plate set 1Nose clip7Air exhaust valve2Breathing hose8Air bag3Hoop ...