These popular conical-bottom centrifuge tubes are made of ultra-clear polypropylene copolymer. ● Material:PP ● Color:Clear ● They feature printed graduations and smooth inner walls for easy filling and sample preparation ● Printed writing area on side allows for permanent coding. ● Autoclavable at 122°C (251.6°F); freezable to –90°C (–130°F) ● Caps are available in two styles: flat, with a smooth surface for additional labeling options and plug style for a secure seal when using shakers and horizontal incubators ● Caps must be loosely attached to tubes when autoclaving