It is LOUD. It does not require batteries or compressed air. If you are lost in the wilderness (or feel threatened in an urban area), a few blasts from this horn will quickly bring help. A safety horn can be a lifesaver. Keep a horn with you on your boat, while hiking or walking in the city in case of an emergency.
Self-powered, compact horn produces a super loud blast of sound that can be heard for over one mile
Animal alert - frighens off unfriendly animals
Reliable - no compressed air or batteries required
From the packaging:
With your mouth, blow in to the hole on the side of the horn. The compact horn produces a super loud blast of sound up to 120 dB that can be heard for over one mile.
Durable polypropylene construction is waterproof and floats.
Other membranes such as PVC, nylon, rubber, even paper can be used in an emergency situation if original membrane should break.