if you order more than you actually use on your door sills, save the film. you can apply it to many places. i applied a 12x3 piece to my rear bumper. i always seem to smack my trailer hitch into my bumper when attaching the trailer to the car = now it doesnt scratch my paint up anymore!

i also attached a couple random pieces in random places on family cars. it works great, and pretty much disappears from view.
prep work is key. if you dont clean & degrease the area well, it will peal off (like any sticker). so make sure you use your dish-washing soap & water solution and clean the area a couple times. its key to remove all wax, road grime, oil from puddles, etc.