The Seal-Once 5 gal. Semi-Transparent Water-Based Marine-Grade Stain provides protection and stability for wood that finishes and performs, as well as an oil base, and withstands harsh environments near open water. Water based, eco-friendly and ultra-low VOC ensures the product is safer for people, pets and plants and is non-hazardous to aquatic life. Formulated to penetrate below the surface, creating a flexible and breathable barrier that expands and contracts with the elements, resists abrasion, plus protects against UV fading and water damage. For use on docks, decks, fences and siding. Use the marine-grade stain to seal and protect up to 10 years on vertical surfaces and 6 years on horizontal surfaces.