This new Gel formula "sticks" to fiberglass where applied for maximum cling time and cleaning power. Stain remover eliminates "yellowing" and tough waterline stains. Completely covers stains to penetrate and dissolve them. Specifically formulated to remove the toughest stains, including rust, dried fish blood, and leaf stains. Fiberglass stain remover spray works on all fiberglass and painted surfaces. Ideal for vertical surfaces.