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While still listed on the BBQs Galore website the Bar-B-Chef smokers are discontinued. You could try to contact them or grill parts .com which carries bar b chef parts. It's something you can easily make yourself with steel or aluminum scrap and a push nut. Make it a little oversize so you dont have to be exact for seal and rain drips off oversize edges instead of seeping inside exhaust around flush edge. If you don't use it while smoking, anything will suffice so to keep weather out such as a can or small ash bucket.