TDS-3 Handheld Pure Water Testing Meter For Total Dissolved Solids With Carrying Case. HM Digital. Features Ideal for commercial use. Includes a carrying case with belt clip. Highly efficient and accurate due to its advanced microprocessor technology. Hold Function: saves measurements for convenient reading and recording. Auto-off function: the meter shuts off automatically after 10 minutes of non-use to conserve batteries. Measurement Range: 0-9990 ppm. From 0-999 ppm, the resolution is in increments of 1ppm. From 1000 to 9990 ppm, the resolution is in increments of 10ppm, indicated by a blinking 'x10' image. Built-in digital thermometer Display: large and easy-to-read LCD screen. Factory Calibrated.