Features 1、MULTI FUNCTIONAL: The pen type water quality tester can measure PH, EC, TDS, simply press the MODE key to switch readings. 2、EASY TO CALIBRATE: Equipped with PH calibration powders of 6.86, 4.00, and 9.18, meeting your calibration needs. 3、CLEAR DISPLAY: A large screen display with green backlit helps to read values at odd angles and low light levels. Pressing HOLD key to lock the reading helps to easily record the reading. 4、MULTI PURPOSE: The water quality tester is widely used in DWC hydroponic systems, drinking water, beer, wine, milk, home brewing, swimming pools, aquariums, etc. 5、STABLE READING: Additional chip makes pH readings more stable, reducing interference from mobile phones and other items on the instrument. Specification Item Type: Water Quality Tester Material: ABS Battery: LR44 button battery x 2 (shipped without battery) PH: 0.00-14.00pH EC: 1-9999us/cm TDS: 1-9999ppm Package List 1 x Water Quality Tester 3 x Calibration Powder 1 x Instructions 1 x Storage Box