The Jewell Instruments Model D820 Series Tiltmeter is a high precision submersible tiltmeter for use in fresh and salt water applications with RS232 or RS422 digital output. Using an absolute gravity referenced electrolytic sensor, the D820 delivers superior measurement accuracy with virtually no long-term drift. High-gain units are sensitive to less than 0.0017 mm/m or better. All units are rated to 200 meters waterproof for advanced protection from the elements. Use the D820 "Shallow Water" for structural monitoring, angle measurement and control, platform leveling and more.