The Aquatec Sub-Alert is not only starting to be a major requirement for many dive-aboard and dive operations; it is also an essential piece of gear that will add to the enjoyment of the dive to any buddy team that need to get each others attention underwater. Features: Horn works both UNDERWATER and on the SURFACE. Volume: Underwater 115-125 dB. (Above water range approx 0.5 - 1.0 mile). Horn is very loud above water. Keep away from ears at all times. Three models are available to fit of 95% of the inflators currently available. Fitting Options: AH-150-01: Standard International connector. AH-150-02: Air 2/SS1 ScubaPro Air 2, Tusa Duo-Air and Atomic SS1. AH-150-03: Airsource Aquatec Air-3, Seaquest Airsource, Aqua-Lung Micra, Oceanic Air XS and Zeagle Octoplus.