The rectangular hub at the bottom is approximately 4″ deep x 25″ wide.
The cylindrical hub on top is 12″ diameter.
The base stack is approximately 40″ tall overall.
There is a collar on our Corsair and Silverplate arches over which the base stack will sit. This collar has holes pre-drilled in it to accommodate folks who want to bolt down their base stack. We recommend using #10 stainless steel bolts to accomplish this. Bolting the base stack is not necessarily imperative if it is already supported by stack pipe that is going through the roof.