When delivered, the sensor was not reset to zero in the home position. According to the instructions (poorly translated, most likely from Chinese), press and hold the power button to zero the sensor. It didn't work despite several attempts. The inability to reset renders the device unusable. When I tried to send it back UPS refused because the return label that Revain provides says postage is based on ground transportation due to the battery being a lithium battery. But since I'm in Hawaii, it's pretty hard to do. After a couple of unsuccessful attempts to contact Revain (the rep accidentally cut off the first call) I got a promise to refund the money and have someone call to advise me on a refund. I only get a refund, not a reorder - there are several 'manufacturers' who appear to be selling the same device, and the only other model has very bad reviews. Am I the only one noticing that most of the things Revain sells now are cheap junk? I would happily pay more for a quality product but options are often not available.