CELLTREAT 50mL Sterile Centrifuge Tube. Packaged in reusable/recyclable plastic racks in a case of 300. Graduations are printed in bold easy-to-read black ink and are accurate to ± 2%. 50mL tubes include a black printed 50mL graduation line and 1, 2 and 3mL graduations molded into the conical bottom. All tubes are manufactured from medical grade virgin autoclavable polypropylene and have smooth, flat surface polyethylene (HDPE) caps. Reusable/recyclable rack design prevents sticking/freezing to surface. Centrifuge tubes can handle a temperature range of -80°C to 120°C.