The Camco Aerosol Signal Horn Refill Canister refills Camco's Aerosol Signal Horn (50164). It produces an extremely loud noise that can be used for personal safety, sporting events, camping, boating and other applications. Once refilled, the signal horn is audible for at least 1 mile and meets U. S. Coast Guard requirements for boats less than 65. 6 feet/20m. Size: 5. 5 oz.