Smart Portable TDS Meter w-ATC, range - 10 to 1990 These smart meters are low cost portable meters with no unnecessary frills. Comes complete with electrode 9v battery and calibration solution.Group features portable meters with high accuracy and these other attributes: Faster Processor with The New Chipset and Motherboard 100% Larger & Easier To Read LED Display Smaller, Ergonomic & Lighter Case Design Easier & Faster To Calibrate Longer Battery Life