5" x 5" SuperPost are the same line drawings as above. The dimensions are as follows below: 

Length: 5" x 5" SuperPost is only available in 36" length
Outside Dimensions of sleeve: 4-15/16" x 4-15/16"
Outside Dimension of Cap: 5-1/2" x 5-1/2"

SuperPost Cap Dimensions
 Bottom cap
4 x4 SuperPost Sleeve sections are available  in  18"- 24"- 36"