inside the edges of the spoilers and between the spoilers and body. supposed to keep water out from the mounting points etc. I found it easier to seal the mounting points because the spoiler may not always have a perfectly contoured edge to fit the body, in which case the oem protector becomes useless. I would still find something to use to put between the wing pieces and body just to keep your paint in good condition and to provide a source of cushion/spring for the mounting hardware. Also, I tried to go the route of OEM mounting hardware, purchase all brand new clips etc etc. I was extremely unhappy with how the OEM mounts worked, hence finding a different way to do it.