pH 55 Specifications Range -2.0 - 16.0 pH Resolution 0.1 pH Accuracy ± 0.1 pH ATC Automatic Calibration 2 Points - Automatic User select 6 Buffer Types Environment 32 - 122F Display LED & Push to Hold Auto-Off After 8 minutes of non-use Battery Life 300 hours of use Battery Type 1.5v Button - 4 Included