Standard Inine dual TDS meter (monitor) This high quality inline dual TDS monitor is distributed by Filter Direct Co. Model: DM-1 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: 1/4" standard, also available with 3/8" or 1/2" at additional $8 charge; 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.) Measure the tap water coming in vs. the purified water going out of your system at any time. Use the meter to determine when the filters need to be changed. Install on industrial systems such as car washes, window washing, manufacturing, and food processing.