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Here's my analog Masterbuilt with a 2" UDS stack. AMNTS tube works well in it. I have a similar size hole in the bottom. To seal when not in use I place a small flat plate over the bottom hole and just close the top. I do caution you if you run the smoker with the vent wide open like I have in this pic you run the risk of the AMNTS flaring up. I found out the hard way smoking some fish.