Falcon Sonic Blast Signal Horn 5oz Refill Refill for Falcon Sonic Blast Signal Horn and Falcon Sonic Blast Signal Horn - Chrome The Falcon Sonic Blast Signal Horn uses HMO1234ze, a specially formulated, non-flammable propellant that has a very low Global Warming Potential GWP. The Sonic Blast Horn is a great option for uses where flammability is a concern, including manufacturing plants, confined spaces, construction sites, boating, and emergency alarm stations. Provides up to 56 blasts per can