Not if you look after it. Clean and dry both the magnet and the door before fitting, and take it off once a week to wipe underneath. Damage happens when grit and water sit trapped under a magnet for months, not from the magnet itself.

They are printed on 30mil magnetic sheet - thick enough to hold at highway speed on a clean flat panel - with UV printing and rounded corners so the edges do not catch wind or lift.

We print 12 x 12, 18 x 12 and 18 x 24 inches. 12 x 12 suits a car door, 18 x 12 is the most common size for a van or pickup, and 18 x 24 is a large format for a box truck or trailer panel. Measure the flat area of your door before choosing.

A 12 x 12 magnet is $39, 18 x 12 is $45 and 18 x 24 is $59. Most businesses order two so both doors match - there is no discount for the pair, but a matched set looks considerably more professional than one.

On a clean, flat, steel door, yes. It will not hold on aluminium or fibreglass panels, on a curved or ribbed surface, or over a body line. If your vehicle has aluminium doors - many newer trucks do - a magnet will not stick and you want a vinyl decal instead.