These brackets are very heavy duty, I used the 4”x 4” and 2” x 4” timber, the brackets are slightly bigger but it makes no difference. I set the 2”x 4” on top of the legs to spread the load. The bench is built to 36” tall 24” wide and 72” long. I can’t get this bench to flex even using my 19 stone. This is a very good kit, I did have to add large penny washers as the ones supplied are a bit thin. All you need to do is cut the wood to length drill the holes, assemble and screw on the top and bottom shelf. You will have a rock sold bench that’s very heavy duty, and heavy, very heavy but that’s good in my book.