The HM Digital DM-2 commercial inline TDS (total dissolved solids) monitor has two probes to measure TDS for feed and product water when used with TDS water filtration systems (sold separately), and can be used for applications including automobile and window washing systems, manufacturing, and food processing. The monitor has a 0 to 9999ppm range. The 0 to 999ppm range has a resolution of 1ppm, and the 1000 to 9999 range has a resolution of 10ppm. The monitor is factory-calibrated to NaCl 342ppm, and is capable of recalibrating each line separately. Shielded cables prevent interference that can cause inconsistent or inaccurate readings. Diagnostic error message features provide troubleshooting assistance. The monitor is 2.6 x 4.6 x 0.7 inches/6.8 x 11.6 x 1.8cm (H x W x D, where H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back). It is powered by 2 AA batteries (included) and has an automatic shut-off after 3 minutes to conserve battery life.