4x4 Post CapsOur 4x4 fence post cap is made to fit nominal sized posts (3.5" x 3.5"). Common fence posts are nominal sized but we always recommend double checking before ordering. If your post is a true 4x4, please view our True 4x4 Post Cap collection.6x6 Post CapsJust like our 4x4 cap, our 6x6 fence post cap is made to fit a nominal sized post (5.5" x 5.5"). We also have a True 6x6 Post Cap collection. Decorative 6x6 post toppers 4x6 Post CapsOur 4x6 post cap is made to fit a nominal 4"x6" post (3.5"x5.5"). Unfortunately, we do not offer a true 4x6 post cap due to its odd size. Post ToppersOur fence post toppers are made to bolt onto the top of any type of wood post. Although they don't add as much protection as our fence post caps, they still keep some water and bugs out while adding a very decorative metal touch to your posts! Instillation is easy for these. All you need to do is place them on your post and secure them with our color matching screws.Our metal post caps are made to fit tight so your fence post, mailbox post... will stay looking new for longer. As a result of this, some trimming of the post may be necessary. Installation Instructions are included in each package and is also on our website.