The Knights by Day Play System is great for all older kids. The fun castle theme stands out in a major way. From the decorative castle roofs to the neatly molded panels, Knights by Day Play System is more than just your ordinary theme playground. The tube slide features our unique see-through section allowing better supervision of the tunnel. With four slides and multiple levels of play, kids will be entertained for hours at a time on the Knights by Day Play System. The Knights by Day Play System includes 4.5-inch diameter uprights.