DM1 TDS Water Meter - Dual Mode - Installs Inline - HM Digital DM1 - Check the TDS level with the push of a button. Now you can easily check to make sure the water from your reverse osmosis system is top quality. Measure the tap water coming in vs. the purified water going out of your system at any time. Very easy installation. Simply cut the line out from the RO membrane housing and install the inline probe between the membrane housing and the shutoff valve, when possible. The closer to the membrane housing the better. Insert the ends of the tube into the John Guest quick connectors on the TDS meter probe. Then cut the inlet feed water line to the system and install the other T/probe. 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) Power source: 2 x 1.5V button cell batteries (included) Battery life: over 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.) Always know if your RO membrane is performing correctly!