This is a castable and rechargeable fish finder with clear color screen for avid fisherman. It is suitable for fishing from a kayak or boat, casting from the shore or using for ice fishing. You will be able to learn the depth, temperature and bottom contour of water that don't have topographical maps, and find where the fish are in the water.Feature: 1. The handhold units and the sonar sensor both are rechargeable 2. Easy to use: tether the sensor with fishing line (not included) and cast it onto water. 3. 20-level Sensitivity 4. 10-level backlight brightness. 5. Two Background Mode: White and BlackSpecification: 1. Display Display Size: 2.6inches 2. Sonar Depth Range: 2.6-131FT/0.8-40M Sonar Beam Angle: 90 degree Operational Temperature: 14°F to 122°F(-10°C to 50°C) 3. Power Supply: Display Unit: Built in Polymer battery 3.7V Sensor: Built in Polymer battery 3.7V Battery Life of Display: If backlight set to be 10%, the battery life will last about 6 hours ( fully charged ); If backlight set to be 100%, the battery life will only last about 3 hours( fully charged ). Battery Life of Sensor:6-8 hours ( fully charged ). Package includes: 1. Handheld display 2. Sonar sensor 3. User Manual 4. USB charging cables for handheld display 5. USB charging cables for sonar sensor 6. Neck strapAttention/Tips: 1. Its reading might be interfered by other high power sonar fish finder close to your fish finder. 2. Please prevent the sensor from crashing into rocks or other hard items. 3. Strong waves, suspended matter and muddy water, might affect its performance. 4. Oil, dirt would adhere to the surface of the sensor and will affect the sonar sensor's performance. Please make sure the surface of the sensor is clean.