Lutron PDO-519 Water Resistance Dissolved Oxygen Meter

Lutron PDO-519 Water Resistance Dissolved Oxygen Meter, Dissolved Oxygen 0 to 20.0 mg/L, Circuit Custom One-chip of Microprocessor LSI Circuit, Data Hold Freeze the Display Reading, Air Oxygen 0 to 100.0 %, Temperature 0 to 50, Resolution Dissolved Oxygen 0.1 mg/L, Sampling Time  Approximately 1 Second, Dual Function LCD Display, Operating Humidity, Weight 194g.