Measure the tap water coming in vs. the purified water going out of your system at any time. Use the monitor to determine when the filters need to be changed. Install the meter for your customers so they'll always know how their system is performing. Features: Displays TDS levels of the feed water and product water with in out electrode probes. Highly efficient and accurate due to its advanced microprocessor technology. Auto-Off function conserves battery power. The unit shuts off automatically after 10 minutes of non-use. Dual Range 0-9990 ppm (From 0 - 999 ppm the resolution is 1 ppm. From 1000 to 9990 ppm, the resolution is 10 ppm, indicated by a blinking 'x10' image.) Factory Calibrated: our meters are calibrated with a 342 ppm NaCl solution. Meters can be recalibrated with a mini-screwdriver. Comes equipped with John Guest Quick-Connect T-fittings as shown. Installs quickly and easily. Specifications: Range: 0-9990 ppm Accuracy: ?2% Cable Length: 24.5" (including sensor) Fittings: 3/8" Quick Connect JG tee Power source: 2 x 1.5V button cell batteries (included) Battery life: approx. 1000 hours of continuous use Size: 7.6 x 2 x 4.7 cm (3 x .8 x 1.9 in.) Weight: 79.4 g (2.8 oz.) Additional Details ------------------------------ Material: Plastic