SmokerBuilder.com

Im new here an thanks for the add by the way. My question is im building my first reverse flow smoker. Out of an old air compressor tank. Thats 20" X 48". It say by the pit calculator that i need a 10 1/4" half moon openning between FB an CC. But it doesnt say if its high or long.

Ok i have A question. By the pit calculator, it says that i need a 10 1/4 inch half moon opening from fire box to chamber. So is that how wide or.how tall it needs to be