A loud gas fog horn is an essential part of a boats safety kit. Also great for starting races etc. The kit contains a detachable, screw fit horn with push button operation.
The gas canister contains 380g of propellant with full instructions for use with the relevant signals for SOS, signalling boat movements and vessel status whilst in fog. Ozone friendly, the canisters are easily replacable.  Acoustic range of approximately 1500 meters.