These polka-dots are *NOT PLASTIC BACKED* unless specified in notes at checkout. Comes in a 30" long strip. The amount of polka-dots you get will depend on the height you choose. The dots are 1" tall by default. If you want a size that is not listed or if you have any questions feel free to use the "contact us" at the bottom of the website.. For tips on how to apply overlays we suggest YouTube; they have some great tutorials on there.