The square base is 4ft square and one foot thick. Below this is a 2' by 3' by 3' block of concrete. The pier is 16" in diameter. It has three 3/4" Stainless steel bolts in a triangular pattern, and a 2" piece of PVC tubing to carry power and control wires to and from the 'scope, under the slab. You can see the tubing exiting the pier from the corner of the square.