Lutron PDO-519 dissolve oxygen meter has 0 to 20.0 mg/L x 0.1 mg/L range, 0 to 50 oC, oC/oF temperature, automatic temperature compensation, probe with the meter all in one, polarographic type oxygen electrode data hold and record, IP-67 water resistance, external calibration buttons, DC 1.5V battery x 4. Made in Taiwan.