Ideal for all water purification applications, wastewater regulation, aquaculture, hydroponics, and colloidal silver. Perfect for both consumer or commercial use. Carry one in your pocket or toolbox at all times! 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: our meters are calibrated with a 342 ppm NaCl solution. Meters can be recalibrated with a mini-screwdriver. Also available in "x10" mode: reads in increments only of 10 ppm (0-9990 ppm).