Useful for collecting and transporting biological specimens. Leakproof characteristics are ensured by a flat top plastic screw cap with an inner sealing lip. Molded graduations from 2.5 to 50ml. Can be autoclaved and will resist temperatures up to 121°C. They will also resist acids, solvents and alkalies at room temperature. They withstand centrifugation speeds of 3000 g or 5000 RPM. Polypropylene tubes only can be autoclaved and resist acids, solvents and alkalies.