Made of prime virgin polypropylene Graduations are printed in bold, accurate, and easy to read Special design on cap, easily open by one hand Max rotate speed up to 12,000g for 15ml tube and 9,500g for 50ml tube Autoclavable at 121°C and freezable to -80°C Sterile packed in foam rack Certified DNA, DNase, RNase free, and non-pyrogenic