i bought this unit to put smoking pellets on, these are 20lb bags of wood pellets.  After I assembled the unit ( You can throw away the directions there junk), I put 3 bags stacked on top of each other so 60 lbs, the shelves sag approximately 3 inches.  I have very little hope these shelves would work for anything other than light items.  The discription says 800 lbs per shelf, I'd guess more like 100 lbs spread out evenly.  I'll buy some other shelves somewhere else.