The compact and portable Milwaukee Dissolved Oxygen Meter delivers fast and reliable readings of the amount of dissolved oxygen in your hydroponic system or other aqueous area. It calibrates easily in two different points: at 100% saturated air and in zero oxygen solution. It also has an automatic temperature compensation to guarantee the highest accuracy. Other features include its small, ergonomic design; large and easy-to-read LCD display; “low battery” warning; easy-to-replace screw-on cap membranes and long battery life. Included with the meter are the polarographic probe with three meter cable, calibration screwdriver, two spare membranes, electrolyte solution, battery and instructions. Also useful in beer micro brewing.