Last month we started a project building a deck . We ran into all sorts of decisions with deck materials and sizes of posts , post sizes where a big thing as they set a size and make a statement , we found that when choosing a post size you should also consider finding a cap to fit the chosen post size , we found all sizes from 2 inch to a full 6 ½ inch size at one site , and they had many color choices , matching post caps and deck lights in low voltage , 110v line voltage , and solar in sizes like 2 inch , 2 ½ in. , 3 in. 3 ½ in. , 4 inch for vinyl , 4 3/8 inch for composites , 4 5/8 inch for all the new composites out recently like veranda brand by home depot and 5 inch for fences and decks , 5 ½ inch for 6x6 wood posts , a full 6 inch for custom made or vinyl fence posts and a 6 ½ inch for even larger jobs , they had it all in this one site with the wire , transformers and more my one stop for outdoor living enhancement