Apera Instruments AI311 PH60 Premium Waterproof pH Pocket Tester, Replaceable Probe, &plusmn;0.01 pH Accuracy, -2.00-16.00 pH Range Accuracy: 0.01 pH; range: -2.00 to 16.00 pH, 32 to 122F (0 to 50C) Easy 1-3 points auto. calibration, recognizes 5 types of solutions (1.68, 4.00, 7.00, 10.01, 12.46); Auto Temp. Compensation (ATC) ensures accuracy in various temperatures (32-122F) High quality replaceable glass pH probe, suitable for regular water solutions e.g. pools&spas, hydroponics, environmental monitoring, cooling towers, beverage, etc. Large LCD with 3 backlit colors (indicating different modes), dual display of temp./pH, and reminders of completed calibrations and stable readings The smiley icon indicates stable readings so you won't have to guess when is the right time to record the measurements COMPLETE KIT with READY-TO-USE calibration solutions, calibration bottles, storage solutions, AAA batteries, and a lanyard all in a rugged portable case