Molded from high quality medical polypropylene material, produced in a clean room, these premium cryo tubes withstand temperature low to -196°C under gaseous phase of liquid nitrogen. The special cap pf external thread design and with silicone rubber liner gasket eliminates the possibility of liquid leakage and cross-infection, greatly ensuring specimen safety. The cryo tubes feature large white writing surface for specimen identification, delivered with optional colorful inserts onto the tube caps for specimen differentiation. Features: Made of medical grade PP material, autoclavable, Withstands temperature from -196°C to 121°C with a maximum pressure tolerance of 95kPa, East-to-read printed graduations, deliver accurate measurement, Special cap design & silicone rubber liner gasket insure leakage-proof, Gamma sterile, DNase free, RNase free and Non-pyrogen.