FSR Fiberglass Stain Remover - 16oz 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.