Old Masters Exterior Oil-Based Spar-Marine Varnish is a durable exterior coating for use on wood surfaces. It contains ultraviolet absorbers for advanced sun protection. Use on exterior surfaces such as fences, railings, lawn furniture, doors, boats and marine surfaces. For interior use on windowsills and door frames for added ultraviolet protection. As with all exterior clear finishes, this product will not offer unlimited protection against the elements. Surfaces which receive direct sunlight may have to be recoated annually to maintain gloss and to prevent cracking and peeling.