The do200a combines low cost with a rugged, waterproof design--making it ideal for spot testing in wastewater, surface water, or aquaculture. Meter features easy-to-use interface, one-hand operation, and results in mg/L (ppm) or percent saturation with temperature, salinity and barometric pressure compensation. Meter also has easy-to-replace membrane cap, auto shutoff, low battery indicator, and nonvolatile 50 data sets memory with calibration. Meter Kit adds: polarographic probe with 4-m cable, and hard carrying case accurate, economical do measurements automatic temperature compensation manual input for salinity and barometric pressure compensation easy-to-replace screw-on cap membranes.