Konvio Neer Imported Total Dissolved Solid Meter(TDS Meter) for RO water with a digital LCD display that can measure, In just a push of a single button, the digital water tester will read the overall water purity level, which will be displayed on the digital LCD panel. This Meter is ideal for all water purification applications, thus to check whether your water filter is doing its job right and when to change the filter. It is very easy to use; all you need to do is to put it in the water and test. Quick Glance at Directions: Testing your water using a Konvio Neer meter is the easiest way to measure for total dissolved solids of the water: Remove the protective cap Turn the Meter ON Immerse the meter into the water up to the maximum immersion level Lightly stir the meter to dislodge any air bubbles and wait for the display to stabilize Press the hold button to view the reading out of the water Turn off the meter, wipe and dry the electrode off before inserting it back into the protective cover