Searchtech Instruments DO-66 Pen Type Intelligent Dissolved Oxygen Analyzer.
It is designed for on-site operation and is portable.
It measures dissolved oxygen (DO) from 0-199.9% or 0-16.50 mg/L and temperature from 0-50°C (32-122°F).
It features automatic temperature compensation and push-button auto-calibration.
The device is powered by two AAA batteries