Special selected high-clarity polypropylene assures the manufacture good transparency, chemical resistibility and obdurability. Furthermore, the universal design make the tubes are suitable for most brand of centrifuge. All the features allow them be widely used in chemical and life science research. Features: • Available with 2 volume of 15 and 50 ml • Conical bottom and self-standing bottom • With a large unerasable frosting white printed writing area provide easy and legible mark • Both the graduations and writing areas are chloroform-resistant • Engraved graduation at the conical portion of the tube • Max rotate speed up to 9,400g for conical bottom tubes, while 6,000g for self-standing tubes • Autoclavable at 121°C and freezable to -80°C • RNase-free, DNase-free, DNA-free, and Non-pyrogenic • Re-sealable bag of 25 pcs.