DiveAlert Plus V2 Air Horn Surface and Underwater Signalling Device ​DiveAlert PLUS is a specially designed, small, light weight pneumatic signaling device that uses quick-connect/disconnect hose couplings to become an integrated part of your power inflator. Installation is easy and takes only a moment. DiveAlert PLUS uses a small amount of air from your SCUBA tank to make a piercingly loud sound in air or water. People have been able to hear a DiveAlertPLUS one mile away from a diver in need above water. Underwater you can sound for attention quickly with a squeeze of the device. In conditions where visibility is limited, a DiveAlertPLUS can be a life saver.  Features Surface and Underwater Signaling Device On the surface a blast of sound that can be heard up to a mile away Great for getting your buddy\'s attention underwater No Mods Required: DiveAlertPLUS does not require any modification to your equipment, and it does not interfere with the normal operation of your equipment. The DiveAlertPLUS comes in three different models to accommodate different connectors: DV1, DV2, and DV3:​ DVI Standard Fitting - Compatible with most standard power inflators except jackets fitted with an Alternative Air Source. DV2 Fits: Seaquest Airsource including Airsource 3 QD, Mares Air Control, Oceanic Air XSand Aries Air Link. DV3 Fits: Tusa Duo Air, Scubapro Air 2 (All Generations ), Zeagle Octo Z, Sherwood Gemini alternative inflater regulator systems. Easy To Use Design: Once the tank is turned on and the DiveAlertPLUS connected, squeeze the DiveAlertPLUS softly underwater for a subsurface signal. Or squeeze it firmly on the surface for a loud surface signal blast. Check that the DiveAlertPLUS is installed correctly and functioning properly before every dive. Also be careful not to point the DiveAlertPLUS toward yourself or toward anyone who is in close proximity to you when you activate the surface signal (it’s really loud!). Attention: Do not point the DiveAlert PLUS towards anyone, as it could cause hearing damage. It is that loud. Maintenance: After each use, the DiveAlert PLUS should be soaked with warm fresh water. This is especially important after use in chlorinated swimming pools and in other water having corrosive substances. Additionally, it is highly recommended that you blow the water out of the DiveAlert PLUS before storing. This can be done by pressurizing and activating both the surface and subsurface signaling elements. (We recommend that you cup your hand over the surface signaling element to muffle the loud noise.) What to do if your DiveAlert PLUS is just blowing air - no sound If your DiveAlert is not screaming with the obnoxious 130 dB blast you\' have come to know and love, here is a quick video to possibly solve that issue. Test for sound after this process. Why use DiveAlert PLUS? What would you do in a diving emergency if you needed to get the attention of someone else? Above or below the water’s surface! Traditionally, SCUBA divers have relied on whistles as their only audible surface signaling device. But, if a diver is disabled and can’t blow into the whistle, the whistle makes no sound at all. Equally frustrating and dangerous, if a diver needs to attract the attention of someone who is too far away to hear the whistle, the whistle is of no help. Or, what would you do if you wanted the attention of your dive buddy, for whatever reason, and he was simply distracted and not paying attention to you at that very moment? Traditionally, you would be forced to swim up to him or her until you got their attention. In contrast, the DiveAlert PLUS enables divers to generate a loud blast of sound on the surface that can be heard up to a mile away! Or, the Dive•Alert PLUS can signal a dive buddy underwater! When you need to get someone\'s attention while on the surface, you simply squeeze the DiveAlert PLUS and it diverts a small amount of air from your scuba tank to make a powerful and piercing sound. Or, when you are underwater and want to attract attention, squeeze the DiveAlert PLUS and it diverts a small amount of air from your scuba tank to make a buzzing noise to alert your dive buddy.