The V2 Pure TDS (Total Dissolved Solids) Monitor, is an in-line digital TDS monitor which measures and provides a highly accurate 'real-time' display of total dissolved solids levels before AND after water passes through the Reverse Osmosis system, providing a visual indicator of its performance Product characteristics at a glance:Real-Time calculation of TDS removal rate with a removal rate indicator. When the TDS removal rate is above 80% the LED glows green and when the TDS removal rate drops below 80% the LED glows red. Dual, 3 digit LCD display with backlight. Easy to use with quick-connect fittings for simple installation. Selectable monitoring mode - battery saving or continuous monitoring using a mains power adapter (not supplied). 1 x long-life 3v lithium battery (CR2032) included. Specifications: Detection Range: 0-999ppm ,Sensitivity: 1 ppm , Accuracy: ±2% , Weight: 25g Dimensions: 110mm (L) x 8mm (W) x 40mm (H)