The pH55 is a Waterproof pH tester with Large dual-level LCD that displays pH and temperature (°C or °F). The large display shows readings in an extended range from -2.0 to 16.0 pH (pH56 has a 0.01 pH resolution) and simultaneously shows temperature from -5.0 to 105.0°C or 23.0 to 221.0°F. They have a stability indicator and hold function that freezes the display for easy and accurate recording. The large display also has graphic symbols to guide you through all operations. Complete with a temperature probe for faster and more precise temperature measurement they compensate automatically for temperature. Calibration is made automatically in 1 or 2 points with memorized standard and NIST buffer sets samples of which are included. Auto power OFF saves battery power after non-use. Part#pH55