Friends .. there are many circles use to build it up. In First cylinder, 2 circle of 1.5inch radius is using. In second, 2 circle of 1inch radius is using 3rd one is build with 2 circle of .75 inch. The circle mount On the top of first cylinder (that means next use of 1.5 inch radius circle) is 2inch in radius. One of my friends want to know that measurement but I am a little late. And that friend delete comment .. sorry friend sorry for late response.