Mines been fine for the 6 months or so I have been using it. It measures . 001 lower than a calibrated refractometer but that's good enough for me. I do spot check it once in a while like all test equipment. I think like most things newer the people who are unhappy comment and the people who are happy just don't bother or have the time because they are enjoying their purchase. Such is the online age with all things not just our hobby equipment.