Detailed Product Description HM-702(stand-alone):220V A.C,auto-test for malfunction,sound & flash alarm ... 10% of Natural gas; HM-702(wired):220V A.C,auto-test for malfunction,Output:Relay(N.C& ... of Natural gas;HM-702L(wired,low consumption):220V A.C.,auto-test malfunction,Alarm Output: relay(N.O ... Alarm level: 10% of Natural gas;HM-702R(wireless):220V A.C.,Alarm Output: Radio Signal and Sound&Flash; ...