Requires just a tiny bit of air to activate the horn.

The Hammerhead-Alert is very compact in size. The loud resonating frequency generated by this horn can be heard on the surface approximately 0.5 miles away. The  Hammerhead-Alert is not only starting to be a major requirement for many liveaboards and dive operations; it is also an essential piece of gear that will add to the enjoyment of the dive to any buddy team that need to get each other's attention underwater. The Hammerhead-Alert is an underwater horn that allows you to signal your dive buddy effortlessly by the press of a button.

• Horn works both Underwater and on the Surface
• Apprx surface range of 0.25 - 0.50 miles
• Volume: 115-125 dB (approx)