This is some information on the master forge smoke stack that is listed in the forms smoker modification. First of all it is 2.5 ID with a 1/2 inch flange. That makes it 3.5 inches in dia. I knew that it was going to be small so I had prepared several reducers to sleeve the opening. Wrong The back of the masterbuilt adjuster is stamped into the box. Sure I could have cut it out or just used some caulking to attach it. I thought I would test it out while I was smoking some loin back ribs. At first I was very disappointed when the pellets just would not burn. That was when I realized I was burning pure cherry. They are hard to burn so I normally mix them 3 parts hickory to one part cherry. When I got that fixed and burned 100% hickory it worked great. The Question To stack or not to stack. I think is answered for me any way. By not attaching the stack I can wash it with out any hassles and by removing it and storing in the smoker It can't damage the cover. I have taken some shots of the air draw with and with out the stack I will post them if they come out. 53 card posted the information in a post about his mod. Ordering information for the stack Service Dept # (800) 963-0211 hrs 8am-6pm M-T 8am-5pm F EST The lowes model number is 0190449 They said that they didn't' use the model number for the part but used the item description but here are both Smoker Stack - 302-02009-00 On the assembly instructions its reference id is H I found the price to be 15.98 delivered. The stack is a lowes master forge about 6 or seven inches tall.