3" x 8" or 8cm X 20cm. (magnets are slightly smaller)
Professionally printed vinyl bumper sticker or car magnet
Printed with UV/water-resistant, eco-solvent inks. That means it will remain unfaded for years.
Unlike paper, vinyl stickers peel off easily without leaving a mess. (just don't remove in very hot temperatures, may leave residue)
Apply evenly to a clean dry surface. Also make sure you aren't applying when the surface is too hot. Wait for night or a cooler day if the temperature is over 85 degrees or so. It is important to apply it slowly and minimize creases or bubbles as you go. Don't worry about remaining creases, just flatten them as much as possible and they will barely be visible.