Shows you what is in the water: water depth, approximate fish location (suits for all sorts of fish), fish size(small/medium/big), short & tall weeds, sand & rocks on bottom. Suitable for fishing from a kayak, off the dock, and ice fishing. You can use the fish finder on moving kayak with slowly speed below 5mph (make sure the bottom of the transducer is horizontal). Very portable that you can take it anywhere: It comes with neck strap that allow you to wear it around neck when you are busy on the kayak. And you can easily store the fish finder in your tackle box. The fishfinder is powered by 4 AAA batteries. It lasts 4-5 hours with new batteries in continuous use. It can be used in fresh water as well as salt/sea water. Accurate Depth Reading: The fish finder use sonar to detect water depth and fish location. Sonar Frequency is 200 kHZ. Detectable area is 45 degrees beam angle under the sonar transducer. Detectable depth range is from 3ft/1m to 328ft/100m below the sonar transducer. Easy to Use: Toss the transducer into water and turn on the display unit, it will show you the water depth and approximate fish depth if fish schools passing by. It has 5 user selectable sensitivity; battery save mode; backlight mode ; fish alarm; unit of measure. Setting can be saved when turned off. Wide Detection Range: The deepest detection range of the portable depth finder is 328 feet (100 m). This means you can use the portable depth finder not only at dock, lake where water depth is shallow, but also can use it on sea fishing. Sonar Sensor: 45 degree beam angle in 200 Khz. Sensitivity of the portable depth finder is adjustable. Even water is turbid, it also can work well. (Tips: please select a low sensitivity when water is turbid.)