Falcon Sound Alert Signal Horn 6oz Refill Refill for Falcon Sound Alert Signal Horn. The Falcon Sound Alert Signal Horn is a great choice of safety horn where flammability isnt a concern, such as boating and sporting events. This horn uses HFC152a, a propellant that Falcon has been successfully using in their Dust-Off line of products. The Falcon Sound Alert Horn was tested extensively to ensure it would work as effectively as other horns. Meets US Coast Guard requirements for boats up to 65 20