No.1 F4 is a smartband, it supports IP68 waterproof, 15 days on standby, removable straps, 0.96 OLED display. It is fully functional. It supports heart rate, blood pressure, blood oxygen, these healthy functions, it also supports weather, UV, Altimeter, Air-pressure, these outdoors features. So you can go out without worrying about the outside world. This bracelet is built for sports. It supports multi-sport mode, with the professional sport algorithm, all kinds of sport will be calculated more accurately. It also supports removable straps, there are four kinds of beautiful straps. You can get a free one on the No.1 blog. Here is a video preview.