For pool leak detection. Ind under ground water leaks also! Hydrophone with amplifier, speaker, & headphones. Velcro back with mounting straps for mounting on pool poles. You can hear the smallest of leaks. With over 20 ft. We added a velcro strap to hook it to a pool poll for easy searching from out side the pool. With pocket size battary operated amp. With it’s own speaker, nice and loud with out ‘s hard to miss. We use a raido shack amplifier. We add ear buds too ! We have found that listening for leaks is by far the best way to do. Many common pool leaks can be detected in a matter of minutes. To find under ground leaks put the hydrephone on the ground and cover with a cheep plunger and listen then move on. For pipe leaks place the hydrephone on a hose bibb. If there is a leak, you will hear it running in the pipe. Most cases, the leak won’t be far from the loudest fixture. In most cases when water escapes from the pool it produces a turbulence as it passes through the hole. The highly sensitive hydrophone allows you to pin point leaks by listening for, and locating the source of this noise. Equipment needed: hydrophone, amplifier, pool pole, ear bud if needed. Have pool filled to normal operating level. Turn off pump and heater before performing any test with the hydrophone. Hookup the hydrophone to the amplifier. Attach the hydrophone to the end of a vacuum / pool pole to survey the area. Lower the hydrophone into the pool, turn “on”, and very slowly raise the volume to the desired level. Identify all areas you plan to test. Here are some suggested areas to use your hydrophone. Light niches: move the hydrophone around the outer rim of the light. If you suspect the leak is in this area, remove the light and scan the area with the hydrophone. Main drains and cracks in the shell of a gunite pools. Here are a few tips. Most leaks will create a whooshing type sound that increases in volume as you move closer to the leak. You can get a good idea of the type of sound you are listening for by discharging a mustard like plastic container underwater. Leaks near the surface may be more difficult to detect because of the reduced pressure and resulting turbulence, and the confusing surface noises that are transferred into the water. Thair is lots of how to’s on youtube. If not as described.The item “Hydrophone, pool leak detection water resistant pool mics. UNDER GROUND LEAKS+AMP” is in sale since Tuesday, April 03, 2012. This item is in the category “Home & Garden\Yard, Garden & Outdoor Living\Pools & Spas\Pool Parts & Maintenance\Other”. The seller is “puffyc” and is located in Murrieta, California. This item can be shipped worldwide.