The UW 30 represents a departure from conventional designs of underwater sound sources. Its unique, patented design uses the case's structural enclosure as the sound transducer. Underwater speakers are required equipment for many activities in commercial, luxury resort pools & synchronized swimming events or instructions in Olympic pools. They are used for water ballets & similar water shows. UW 30 has a high-fidelity sound w/low distortion, & the effect of music played underwater through it is truly enchanting. The UW30 underwater speaker is equipped w/a waterproof, 3-conductor 50-foot cable. 8-ohm impedance, available in pool blue. Underwater speakers are required by the American Athletic Union for synchronized swimming events & instructions in Olympic pools. They are also ideal for water ballets or similar water shows & resort or private pools. Built for installation in both fresh & salt water pools, the UW30 can even be safely installed in ocean environments. Designed for permanent installation & completely submerged operation. Problems such as corrosion & electrolysis damage are completely eliminated due to the plastic construction. The 12.7-ounce ceramic magnet & state-of-the-art voice-coil construction assure full-fidelity response w/the lowest possible distortion throughout its power range. One speaker is recommended for pools up to 30 by 30 feet, or two speakers for pools up to 30 by 60 feet.