Wish I could give zero stars... I have been using this wrist monitor for a few weeks now, and I have made sure that I'm following the directions for use. Well, I just took the wrist monitor into the doctor's office, to make sure the readings were similar to the doc's BP monitor - The readings were WAY, WAY DIFFERENT! Off by about 15 points on the systolic and off by 8 points on the diastolic. And we retook the reading multiple times. Very disappointing and very bad for a device that should be better calibrated for something so critical.