This PPM meter provides scales for EC,CF and PPM. It's fully waterproof, factory calibrated with auto off. There are no external switches for adjustments; just dip & read. Ranges: PPM 140-2520, EC 0.2-3.6 (CF 2-36). Resolution
0.1 EC. Accuracy +/- 4% full scale. Operating temperatures 32-122 F (0-50 C). Temperature compensation up to 78 F (25 C). 90 day warranty.