AZ Waterproof pH pens raise the bar in ease of use, reliability, function and price point. AZ meters provide a big IP65 LCD screen with dual pH and temperature display. Wide pH measuring range from 0 to 14 and a temperature range of -5°C to +60°C. Waterproof IP65 keypad with simple one touch auto calibration. Also includes a hold button to freeze current readings in low visibility. ATC (auto temperature compensation) ensures accurate readings in all climates. Auto off function maximizes battery life.