PPCO, PP screw closure. These conical centrifuge tubes combine better separation / pelleting capabilities of a conical tube with the superior sealing capability of Oak Ridge tubes. Graduations silkscreened from 5 to 35 ml in 1 ml increments. Accommodate Nalgene® sealing caps (Order No. 5315739). Required conical tube adapter is available on request. Molded of PPCO for better chemical resistance. Tubes are translucent but contact clear for easy liquid viewing. Must be filled to at least 80 % of the total capacity for proper performance. Autoclavable, biohazard, transparent, graduated, leakproof.