Reliable DO readings at a reasonable price. Measures dissolved oxygen to determine water quality in environmental testing, labs, industrial and municipal waste water, aquariums and fish hatcheries. The back-lit display simultaneously displays dissolved oxygen (in % or mg/L) and temperature readings (in °C or °F). Automatic temperature compensation as well as manual compensation for salinity and altitude. Features simple one-button calibration to air. DO probe heads include built in membranes and screw on and off for easy replacement. Also functions as a pH, ORP, Conductivity, TDS or Salinity meter when used with the optional probes (sold separately). Comes in a hard carrying case complete with one DO probe, two spare probe heads, electrolyte, instructions and a 9V battery. EPA Equivalency Method: 360.1. Meter Dimensions: 7" × 2.75" × 1.25" (177 × 68 × 45 mm) Meter Weight: 16 oz (489 g) Kit Dimensions: 11" × 9.5" × 2" (279 × 241 × 51 mm