These Costar® 0.65mL microcentrifuge tubes are made of colored polypropylene and are certified RNase-/DNase-free. Rainbow pack includes one bag each of blue, green, yellow, red and orange tubes. Supplied nonsterile and are autoclavable. External graduations and frosted writing spot for easy sample identification. Positive seal design allows for repeated opening and closing. Flat cap surface for convenient labeling. Withstands a maximum RCF of 17,000xg.