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 RO system, providing a visual indicator of its performance. �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).