The Clark Synthesis Aquasonic (AQ339, formally AC339) is an economical moving-coil design underwater pool speaker providing louder, more bass rich sound than the UW30. Possible uses for the Aquasonic include providing underwater sound for flotation tanks, watsu massage, synchronized swimming, and integration into home swimming pools. (For 25 yard and 50 meter collegiate pools, or deep home lap pools, the Lubell portable LL916 or in-wall 9484 underwater speaker is recommended based on reports from high school swim coaches.) The Aquasonic is rated at 135 watts continuous @ 4 ohms, and has an attached 100' Enduroflex jacketed 2-conductor cable. Lubell Labs recommends using the Aquasonic with the TOA BG-2120 mixer-amplifier listed below because amplifier is UL listed, has transformer isolated 4 ohm output, and has 3-prong grounding power cord for connection to GFCI outlet. USA and Canada sales ONLY.