Auto-Off function conserves battery power. The unit shuts off automatically after 3 minutes. Dual Range - Measures from 0-999 ppm, with a resolution of 1 ppm. From 1000 to 9990 ppm, the resolution is in 10 ppm increments, indicated by a blinking 'x10' image. Factory Calibrated: our meters are calibrated with a 342 ppm NaCl solution. The DM-2 features digital calibration. Diagnostic error messaging. Shielded sensor cables. Comes equipped with 1/4 inch Mur-lok Quick-Connect T-fittings. Also available with 3/8" or 1/2" fittings. Installs quickly and easily.