If the physical number is worn off or unreachable, you can find it in the Fitbit app by going to Account > Your Device, or via your desktop dashboard settings.
By locating and storing your Fitbit Zip serial number, you can utilize it to verify ownership with Fitbit Support if your tracker is lost and subsequently found by another user. Fitbit Zip Serial Number
Finding the serial number (SN) on a Fitbit Zip is crucial for support, as it is often worn off or tiny on the back of the device. If the physical number is worn off or