The conical centrifuge tubes are made of virgin polypropylene. Easy-to-read black graduations are in 1 mL increments with a large white printed writing area. Smooth, flat surface plug seal caps for conical bottom tubes are included. The tubes are leak proof and withstands up to 12000 RCF. The tubes can withstand the temperatures -80°C. All tubes are Sterile, DNase, RNase, and Pyrogen free.