VERSATILE USE: Marine 31 Port to Starboard Cleaner cleans marine surfaces and home items. Use on vinyl, fiberglass, & upholstery for a spotless shine! POWERFUL STAIN REMOVER: Removes black streaks, mildew, and other common stains that are found in the marine environment. Can also remove salt water stains from your boats' gel coat CUSTOM DILUTION FORUMLA: Use Marine 31 Port to Starboard Cleaner full strength or dilute for specific tasks. MARINE & HOME CLEANER: Marine 31 Port to Starboard safely removes grime from boats and home surfaces. Can also remove salt water stains from your boats' gel coat