Instruct: Classify Amazon reviews into positive or negative sentiment
Query: It seems to work

It seems to work.. I have no way to gauge if it is truly accurate. :) However, when testing a water source before and after it entered our RO filter, it clearly showed that the RO filter was working. Have had this for about 4 months now and it has worked fine w no battery problems.It is good that it has a button to save your reading until you take it out of the water. Without that, sometimes it's hard to read the display while the meter is in the water container.