Petri dish 2 compartments made of Polystyrene, These Petri dishes are transparent and comes with the lids, they ready to use. These Disposable Petri Dishes are made of optically clear, non-toxic, Polystyrene. These 90mm Petri Dishes are packed in a pack of ten in polyethylene bags and are ETO sterilized. , Polystyrene, 90mm X 15mm.