ProWood 4 in. x 4 in. Wood Flat Fancy Post Cap (6-Pack) 189300 - The Home Depot
Wood and Copper Fence Post Caps - Miterless Post Caps™ | Post Cap Depot
75mm DuraPost Metal Post Cap - Galvanised - Fencing Essentials
4x4 Fence Post Cap (3 1/2") Single Pack Decorative Unfinished Aluminum - Mailbox, Lamp Post, Wood Deck, Dock, Piling Caps for Wooden Posts by WeatherPRO Post Caps - Amazon.com