The official decals of the Ford Special Vehicle Registry, they measure 2.75" in diameter and are reverse adhesive so that they can be applied inside of your vehicle's window*.
Depending on your Mustang, it's possible to order multiple decal designs. For example, you might have a Mustang FOX, which is also an SVO or a 1968 Shelby GT500KR, which is powered by a Cobra Jet. Of course you can order the classic Mustang registry decal!
* You must only apply this decal in an area that not obscure your view when driving and complies with motor vehicle laws and regulations.
Currently only available for sale within the United States.