The HM Digital SM-1 In-Line TDS Monitor for Single Water Line checks the level of Total Dissolved Salts (TDS) for a single water line. The monitor features an auto-off function that turns off the system after ten minutes of non-usgae to conserve battery. It is accurate and efficient due to its advanced microprocessor technology. It has Mur-lok Quick-Connect T-fitting (1/4") and range from 0-9990 ppm with a resolution of 1 ppm. The dimensions 7.6 x 2 x 4.7 cm (3 x 0.8 x 1.9 inches) and the cable length is 24.5 inches (including sensor). The accuracy is +/-2% and the conversion factor is NaCl with an average of 0.5.