Rear filters for the Hottop roaster; this includes the plastic filter housing. Hottop recomends replacing these every 20 roasts. I personally have washed them clean, dried them thoroughly, and kept on roasting for a longer than 20 roasts. Really, the machine produces a lot of smoke even with a fresh filter in there. So why not just roast without a filter? Because it changes the way heat is cycled through the roaster ... so keep the filter in there, and make sure it's in reasonably good shape. Ignore discoloration, avoid too much build-up on it. If the roaster is getting too hot - ejecting roasts before they are programmed to end, it could be that you need a new filter. The filter includes the plastic housing, as pictured.