Fsr is a proven Stain remover for all fiberglass and white painted surfaces. Use on boats, rvs and at home on swimming pools and fiberglass shower stalls. Also bleaches cutting boards white again. Take fsr fishing to remove bait and blood stains. Removes water line grunge, rust stains from stainless steel and rust bleeders from fiberglass surfaces. Oxolic acid based is neutralized in water and is biodegradable so it will not harm the environment.