Extech 407510 Dissolved Oxygen Meter Dual display provides O2 or dissolved oxygen and temperature readings Measures dissolved oxygen in water from 0 to 20.00mg/L and oxygen in air from 0 to 100% Resolution: 0.1mg/L DO, 0.1% O2. Accuracy Temperature : 1.5F/ 0.8C Automatic temperature compensation Min/Max/Average record/recall