FSR (Fiberglass Stain Remover) is a unique stain absorbing gel that is ideal for removing oil, rust, exhaust, waterline and transom stains. It can also be used anywhere else fiberglass stains may crop up—shower stalls, furniture, etc. Use for removing road soil from trailered boats and recreational vehicles. Its non-abrasive quality means that it's safe to use on white painted surfaces as well as on gel-coat. Just be sure to test a small area first to be sure FSR will not damage finish. Requires no sanding or compounding. Simply apply with a brush, sponge or cloth. Wait a few minutes and then wipe off or rinse.