The YSI 52 is designed for use in the lab and in the field. With pushbutton calibration, autostable readings and RS232. The meter has a rugged, splash-resistant case. Large display simultaneously shows dissolved oxygen, temperature and time. A low-battery warning lets you know when to change the batteries. Includes 6 D-cells and a 110V power supply. Range 0-19.99 mg/L to 0.01, 0-200% air saturation to 0.1%.