You have to install the flange, it is the same threads as the stock cap. It comes with 2 different rubber seals, depending on witch harley model you ride. I used the flat one I think? You screw the flange on to your tank very ,very tight. the center cap just unscrews with the key( plastic ). I mostly just screwed the cap on finger tight and could loosen it with the palm of my hand. Kept the key on my keychain just in case. makes for a nice flush look.
