I bought this for silent notifications and a silent alarm and neither of those functions worked. The notifications from my phone (FitBit supported model) were so delayed that I missed phone a number of phone calls. The vibration is so weak that I can hardly feel it on my wrist. The silent alarm is pathetically short and weak, so didn't wake me up at all. There is no option to customise the vibration or snooze time. When I reached out to FitBit support, the solutions they offered did nothing to improve the issues. Then the notifications virtually stopped working altogether. FitBit were extremely unhelpful. Returned to nulledpc.com and will not be buying another FitBit product again.