Charcoal box complete.
Inner dimensions are 21"x21"x6". So far my biggest disappointment at myself is the size of the firebox. For some reason it's only about 9" tall so I have a few inches under the charcoal box for ashes to fall and only about 2" above the sides until the heat deflector plate. Wish I would have added another 3" or so even if it meant dropping one of the shelves in the smoke chamber.