The Lubell Labs Underwater Loudspeaker remains the most popular underwater speaker in the world since 1968, as it's patented design is significantly louder and clearer than competing designs and products. This unique design utilizes a dual-piston PVC overmolded aluminum enclosure as the sound transducer, offering true pistonic operation and low Q in a compact corrosion-free package. Coupled with a powerful 8-cylinder piezoelectric engine (with efficiencies approaching 60%), no other brand compares! Because of the increased interest in water aerobics, lap swimming, and synchronized swimming, built-in Lubell 9484 underwater speakers have become a standard feature in concrete Collegiate pools around the world. Coaches appreciate the ability to effectively and clearly communicate instructions to their swimmers via wireless microphones from the deck. When not coaching, upbeat music with select tempos (or metronome beats) can be played for swimmers to keep pace in an enjoyable fashion.