PREFERRED 4″ 1 Piece Base Cover is used to finish off a 4″ Post Sleeve’s Base. It slips over the top of the sleeve and then is shimmied down to the base and then screwed to the base. This base cover needs to be applied to the bottom of the post before any Rail Brackets are attached. The base cover is included with a Post Sleeve Kit. This should only be purchased for replacement or if the kit is not purchased.