The YSI 5000 basic model features menu-driven operation and a large, liquid-crystal display. Auto stabilization lets you predetermine a stable reading. With YSI BOD Analyst Software, the 5000 performs all required BOD calculations. Internal memory for 100 data points reduces the need for manual entry. An RS232 interface allows upload to spreadsheets. When using the BOD software, you can transfer control of the functions to your computer's keyboard. In addition to the features included in the basic model, the YSI 5100 instrument offers built-in software to fulfill USEPA 503 regulations for OUR/SOUR measurement. An internal barometer performs accurate pressure readings and compensation. The YSI 5100 instrument features automated calibration, real-time clocking, and an integrity function that alerts you to membrane damage. Bar code compatability eliminates the need to type or write the bottle number on bench sheets. Battery or AC powered.