Fish Attracting Light: The echo sounder has two colors of bait lights, which are turned on by default. Slide the switch twice quickly can turn on and off the lights. The attracting fish lamp only work on some of the light sensitive fish. Portable and Easy to Use: No bigger than a flashlight, the handheld depth finder is small enough to fit just about anywhere. Simply add four AA batteries and the unit is ready to go with a flip of a switch. All you have to do is place the front of the device in the water and get a reading on its backlit LCD screen. Water Resistance and Durable: Fully waterproof and built to last. It is 100 feet (30 meters) waterproof, allowing you to use it as a range finder or target for snorkeling or diving. Accurate Depth Reading: AdaLov handheld depth finder accurate depth readings up to 300 feet and temperature readings accurate to within 1/10th of a degree. The handheld sonar depth finder has a Large LCD Display with LED back light, making it useable at night. In addition to depth, the unit delivers both air and water temperature readings. Sonar Localization: Fish can be detected by placing the device on ice, use sonar to locate and define the structure directly below the sensor. shoot through the ice before drilling your hole to check the depth or see if there are fish.