The cultivation of cells as mass cultures has become increasingly important over the past few decades and has led to further developments of high-quality products. This includes items such as roller bottles which are used for the production of virus vaccines or recombinant proteins used for therapeutic approaches. CELLMASTER™ roller bottles are made from polystyrene (PS) or polyethylene terephthalate (PET). These materials, like those used for the screw caps (HDPE) and the hydrophobic membrane (PET/PTFE) of the filter screw caps, comply with the quality standards of the U.S. Pharmacopoeia. The complete end product is USP Class VI certified. All roller bottles are sterilised by irradiation.