Graduated, Polymethylpentene Erlenmeyer Flasks With Screw Cap Thermo Scientific Nalgene Excellent combination of clarity, chemical resistance, impact strength and autoclavability Transparent to microwave radiation Use for titrations, preparation and storage of culture media 125 mL has size 33 cap, 250 mL has size 38 cap, 500 mL has size 43 cap, 1,000 mL has size 53 cap.