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 min of non-use to conserve batteries. Measurement range: 0?9990 ppm. Display: large and easy-to-read LCD screen with built-in digital thermometer. Factory calibrated: Our meters are calibrated with a 342 ppm NaCl solution. Meters can be recalibrated with a mini-screwdriver. 1 year warranty.