Fast response, reliable and accurate measurements Impact resistant ABS waterproof housing (meets IP57 standards) Easy 2-point calibration with included pH 4 & 7 buffer solutions Comes ready-to-go with two long-life 3-V Lithium batteries Replaceable electrodes The P771 pH meter is a highly accurate, pocket-sized pH meter perfect for use in field environments and applications. With this meter you can easily and accurately measure the pH balance of liquids. Contained in a rugged, waterproof housing, with replaceable electrodes, this meter will give long durable service. High 0.01 pH resolution and ±0.02 pH accuracy gives you lab quality results at your fingertips. Automatic temperature compensation (ATC) adjusts for changes in pH due to temperature so you can be sure of your results.