Waterproof ExStik II Dissolved Oxygen Meter. Oxygen level displayed as percent Saturation from 0 to 200.0 percent or Concentration from 0 to 20.00ppm (mg/L). Adjustable Altitude Compensation (0-20,000ft in 1,000ft increments). Adjustable Salinity Compensation from 0 to 50ppt. Analog bargraph indicates trends. Memory stores up to 25 data sets with DO and Temperature reading. Self calibration on power up. Data Hold, Auto power off, Low battery indicator. Waterproof to IP57. Optional 3 ft (1m) or 16ft (5m) extension cable with probe weight. Complete with DO electrode, protective sensor cap, spare membrane cap, electrolyte, four 3V CR-2032 batteries, and 48 inch (1.2m) neck strap.