The YSI 550A meter is waterproof, rugged, and reliable Dissolved Oxygen
Meter. It allows simultaneous measurement of dissolved oxygen and temperature and features a backlit display, automatic push-button calibration, and a weighted, quick-sinking probe.
The 550A also has a built-in calibration chamber, low-battery indicator, direct salinity, and altitude compensation. It will calibrate in % or mg/L saturation and displays temperature in user selected degrees C or F.
The DO electrode is easily field replaceable, and the replacement membranes are built into screw-on caps.
Battery life is rated at 2,000 hours. Special 3-year warranty on meter and 1-year warranty on sensor.