Dive Alert Plus Air Horn from Watersports Warehouse watersportswarehouse.co.uk/dive-alert-plus-emergency-signalling-716912.html
Dive Alert Plus Emergency Signalling Device, the only true dual function mergency signalling device for use above and below the surface device. Ultra loud and can be used above and below the water.
On the surface the horn can be heard up to a mile away and by flipping the Dive Alert Plus switch you can attract your buddy's attention underwater.
The Dive Alert Plus is a reasonably lightweight pneumatic signalling device that harnesses the power of compressed air to produce a distinctive sound. Utilising the quick-connect/disconnect couplings on your standard BCD power inflator the Dive Alert Plus easily becomes an integrated part of your BCD. So no modifications are required and will not interfere with the normal operation of your dive gear.
This standard version is compatible with 85% Standard BCD Power inflators (Model DV-1V.2).