The magnet isn't what wrecks your paint. The grit under it is. A magnetic mount clamps down hard, and any dust trapped underneath gets ground into your clear coat every time the vehicle moves. These discs go on first. The magnet sits on top. The film takes the wear instead of the paint.
Set of 4 — one vehicle. Most Starlink Mini magnetic mounts have three or four feet.
Fitting: wash and dry the spot, then wipe with isopropyl alcohol. Apply the adhesion promoter and let it dry off. Peel the backing, lay the disc down from one edge and smooth outward with your thumb. Leave it [24 hrs — TBC] before loading the magnet on. Wipe the top of the disc before every mount — grit on the film is still grit.
Removal: warm it with a hairdryer, peel slow. Any residue cleans up with isopropyl.