The Gothic cap fits externally on a true 4 in. x 4 in. post | Simple to install | Made in the U.S.A. Manufactured from high quality, durable PVC vinyl | Will not fade, discolor or warp | UV Resistant | Water Resistant | Limited lifetime warranty Perfect for a fence, deck, or mailbox post | Maintenance Free: Simply slide the Gothic cap onto your post. Set it and forget it. | Use clear silicone (not included) for outdoor use to secure the cap (optional) Maximum profile dimensions: 4.010 in. x 4.010 in. | Corner Radius: .188 in. | Total height: 7.75 in. | Overall Outside Dimensions: 4.125 in. x 4.125 in. | Color: white Add a unique, finished look to your deck or fence with the Vinyl Gothic Post Cap