These Secure-Lock™ microcentrifuge tubes offer a special locking clasp to produce a more secure closure. This will help to prevent tubes from opening during centrifugation, boiling, storing, freezing and shipping. They are graduated at 0.5, 1.0 and 1.5 ml. They are autoclavable to 121 °C. Pierceable lid. Etched surface on side of tube for sample identification. Certified RNase-, DNase-, Pyrogen- and DNA-free. The maximum centrifugal force is 20,000g.