The HI 9025 is a microprocessor-based pH meter that is housed in a rugged waterproof casings that can measures pH/ORP and temperature. The Auto-Instruction feature guides the user step-by-step through the calibration process with graphic symbols. The automatic calibration procedure is simple and quick and can be performed at 1 or 2 points selected from 5 memorized buffers: pH 4.01, 6.86, 7.01, 9.18 and 10.01. A stability indicator assures a correct calibration. This meter also features an automatic shut-off to save battery life. http://www.hannainstruments.nl/upload/files/manuals/manHI_9023C_9023CN_9024C_9025C_9110_9210_9210N.pdf