This new AQUATEC Duo-Alert is very compact in size. Only the best quality component is used in manufacturing of the AQUATEC Duo-Alert. The loud resonating frequency generated by this horn can be heard on the surface over a 1km. range, and underwater approximately 100 metres.  Features:  Horn works both UNDERWATER and on the SURFACE.  Volume: Underwater 115-125 dB / Surface 123-130 dB.  Horn is very loud, keep away from ears.  Three models are available to fit of 95% of the inflators currently available.   AH-380-01: Standard International connector.   AH-380-02: Air 2/SS1 ScubaPro Air 2, Tusa Duo-Air and Atomic SS1.   AH-380-03: Airsource Aquatec Air-3, Seaquest Airsource, Aqua-Lung Micra, Oceanic Air XS and Zeagle Octoplus.