Fitbit is aware of a fault in the Fitbit Ap which makes it impossible to consistently sync with a Windows 10 device. For Example: If you are planning on syncing your device with a windows 10 laptop you are wasting your money. They do not know when the problem will be fixed. I have been having problems since purchase 6 mo ago. A supervisor ( Michele C) finally admitted the problem today. They will not give you a refund because they claim the warranty only covers the fitbit & that is working. The fact that the ap is defective does not concern them.