YSI 50B Dissolved Oxygen Meter is a microprocessor-based instrument designed to measure dissolved oxygen and temperature in water and wastewater applications. It can be used with any YSI Series 5700 probe, and both the mg/L and the % air saturation modes are automatically temperature compensated for changing permeability of the oxygen probe membrane and for the changing solubility of oxygen in water with changes in temperature. The autoread function causes a tone to sound to indicate that the reading is stable.