Polystyrene heavy wall with screw cap, printed graduations, corrugated wall increasing the growth area from 850cm² to 1700cm² and viewing window for microscopic observation and cell recovery. The surface is specially treated to optimise cell attachment and each batch of bottles is rigorously tested to ensure sterility and lack of toxicity. Individually printed with the batch number to aid traceability. Sterilised by gamma irradiation.