I upgraded my Cfm watch from a pro 2 to a pro 3. Battery is supposed to last 13 days. Measurements of BpM and Blood oxygen as well as sleep are supposed to be more accurate. The watch lost charge within 3 days and recovered somewhat after a firmware update and once the background processes were switched off. Still the battery lasts less than 6 days. The measurements are less exact than with the previous model. I tried to return the watch but was met with such a convoluted and obscure process and endless emails requesting yet another step that I gave up. The company seems to stay just within the bounds of European customer rights but without actually wanting to refund the customer. Beware of the risk