Dissolved Oxygen Meter Lutron PDO-519 DISSOLVED OXYGEN METER, all in 1 Model : PDO-519 * Range : 0 to 20.0 mg/L x 0.1 mg/L. * Temperature : 0 to 50 oC, oC/oF. * Automatic temperature compensation. * Probe with the meter, all in one. * Polarographic type oxygen electrode, professional. * Data hold, Record ( max., min. ). * IP-67 Water resistance, heavy duty. * External calibration buttons. * DC 1.5V battery ( UM-4, AAA ) x 4.