Waterproof to a depth of 150´ (50m), this sounder features a built-in transducer and measures depths in feet or meters in a range of 1.8´ to 260´ (0.6m to 79m). The transducer sends high frequency pulses to the bottom of a body of water where these pulses are reflected back and converted to electrical pulses that are amplified and displayed on the easy-to-read LCD. The seven-digit LCD is backlit for night use. This compact depth sounder transports easily and stores conveniently – it will even slip into a shirt pocket! Powered by a 9V DC dry cell battery (included), the sounder has a battery life of approximately 500 uses and automatically shuts off after 10 seconds. Wrist lanyard included.