Woodway Flat Top Post Cap &ndash; Treated Wood Outdoor Fence Post Cap for Garden, Deck and Patio, 4 x 4, 1 PC Decorative flat top post cap made out of strong and sturdy Western white woods. Wood is treated with a natural oil stain. Post cap adds visual appeal to any fence, deck, mailbox or lamp post. Cap can be used indoors as well. Weather resistant construction that is designed to handle the outdoor elements. SPF wood is known for durability. This post cap prevents water from settling in your posts. Made with quality it will not fade or split at the corners. Easy to install, measuring 4 by 4 inches, made with rabbeted block for a secure fit. Fits 3.5 inch post.