YSI Model 550A Dissolved Oxygen Meter, 12-ft (3.7-m) probe cables

These DO meters feature a built-in calibration chamber that provides a 100% water-saturated environment - perfect for calibrating, transporting, and storing probe. Provide simultaneous readings of oxygen and temperature. Measurements are fast and easy with one-handed operation, large backlit display, automatic push-button calibration, and a weighted, quick-sinking probe. Low-battery indicator alerts you to change batteries. Salinity, temperature and altitude compensations eliminate the need for correlation chart. Polyethylene membrane reduces stirring requirements and improves response time Innovative field-replaceable dissolved oxygen (DO) electrode modules save time and money Waterproof, impactresistant case - IP67 rated