it is cotton lined with a zipper enclosure and has a 4 inch flat bottom. this class was short, only 4 sessions. and the funny thing is you will mostly remember the good times (even if they are only moments), and you will be able to laugh at the bad times… we are funny that way!!! then when i was lying in bed at the hotel in the big empty bed, i felt it. in addition to this destruction, they also cause nuisance and sometimes pain to the beekeeper as well. it turns out it fell apart. 