Dean the meatballs, numbers and decals on my Cobra are permanent while the numbers and decals on the Mustang are static cling. So far I haven't had any problems with them coming off at speed but you must store them flat when not on the car so they don't curl up. Most of the time they stay on the Mustang but there are times when I take them off. Like when I don't want it to draw as much attention
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Dick