Secure-Locke Microcentrifuge Tube, 1.5mL, Yellow, 500/pk (T331-10Y)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.