ETI pH Pal Plus our most popular pH pen The pH Pal Plus tester is a userfriendly and simple to use pH meter that incorporates an automatic calibration feature. At the touch of a button, the instrument will automatically re-calibrate itself when used in conjunction with a 7.00 pH buffer solution. The pH Pal Plus tester will power off automatically after ten minutes, maximising battery life. This pH Pal is ideal for measuring the pH in food processing and water testing applications. The pH tester is an invaluable tool when mixing concentrates with water. The unit is powered by four LR44 button cell batteries (supplied) and includes a protective cap.