Review on UMIDIGI UFit Smart Watch with SpO2 Blood Oxygen Meter, Heart Rate Monitor, 5ATM Waterproof - Fitness Tracker for Men and Women, Compatible with iPhone and Android Phones by Roy Boone

Bought because of the power pack function. Was curious how it works (more on that later). Well done. The app design is better than Apple's. The first time, the hand in the hand didn't seem shaky at all due to the low weight. Battery life 7 days! Accurate step tracking with GPS and altitude. Great job Japan. It turns out that the blood pressure value is determined by blood flow, which is easily measured with a laser. However, the resistance to blood flow is assumed to be constant, which is not always true. For example, after dipping my hand in very warm water and it turns red, blood pressure is higher (increased blood flow) when it should be lower due to decreased resistance (like the electric current equation). After 10 or more calibrations, it is accurate enough for everyday use. Now I don't know what to do with my iWatch; exchange it? and get ripped off a second time, no way.