Record Function: Stores measurements for convenient reading and recording. Versatile Applications: pH and TDS and EC tester can test water purifiers and filters, do temperature monitoring quality of food (vegetables, fruits) and beverages, swimming pools and spas, aquariums, hydroponics. Preservation function: Digital PH meter and TDS EC meter digital tester record measurements for convenient reading and recording. Auto-off function: Digital PH Meter Tester + TDS EC Measure Digital Tester turn off the meter after 10 minutes of non-use to save batteries. Easy to carry: TDS/PH testers are small in size and light in weight like a pen, easy to carry and convenient to carry in your pocket when you go out.