These polypropylene racks hold 25 cm2 or 75 cm2 (50 - 75ml or 250 - 260ml) or similar sized tissue culture flasks in a vertical position during processing of tissue cultures. Rectangular holes in the top and center plates stabilize the flasks. Racks prevent the "domino effect" of flasks tipping one over the other and can be easily and safely handled. Flasks can be more easily organized to improve processing and avoid errors in collecting used medium, medium change, washing of cell monolayer, trypsinization and seeding of cells. Grips on each end make rack handling easy and allow for safe transport of flasks to the incubator. Steam autoclavable at 121°C (250°F).