Usually, no serial number means stolen. There is no need to remove the sticker on the unit becuase the assembly screws are not under the sticker. Escort sent us an alert last week saying that people are buying X50's, taking them apart, swapping internals with an old 8500, and trying to return them to the store. If it is an X50, it will say so on the display during power up. Refurbished units will still have a serial number.