When you include the padding, the diameter of the poles are approximately 1.5" all around the cage. Each support pole and arch are made up of multiple poles that are inserted into each other and the diameter of the poles inside of the foam vary, according to whether they have steel in them or not and whether they are part of the bendable arch or not. You can get more information about each specific pole section's inner dimensions by contacting Heater Sports directly at 800-492-3994.