McKesson Centrifuge Tube Plain 15 mL Screw Cap Polypropylene Tube (1082080_CS) 500/CS15 mL centrifuge tubes come with blue screw caps. 17 x 120 millimeters High quality, translucent tubes are molded from polypropylene material and have a conical bottom. 8,078xG 8500 RCF spin rate Black printed graduations in 0. 5 mL increments for easy measurements Large, white printed writing space for convenient labeling Sterile tubes are autoclavable (without cap) for continued use. Blue screw caps made of high density polyethylene (HDPE) are flat