CellPro™ Cryovials are designed for safe storage of samples at temperatures as low as -196 °C (gas phase of liquid nitrogen only). Cryogenic Vials with externally threaded caps have a special screw cap designed with silicone O-rings to avoid the risk of sample contamination. The silicone O-rings allow for expansion and contraction in liquid nitrogen environments associated with long term, -190°C storage. CellPro™ Cryogenic Vials are manufactured from high visibility polypropylene for stability in extreme temperature conditions. CellPro™ Externally Threaded Cryogenic Vials provide a safe and secure tube for ultra-low temperature storage of valuable cell cultures, clinical hospital samples and biological samples. All CellPro Croyvials are sterilized by E-Beam and are non-pyrogenic, DNase/RNase and human DNA free.