Greiner Bio-One Cryo.s™ cryotubes are made of transparent polypropylene and have been developed for the storage of biological samples up to -196 °C. Greiner Bio-One cryotubes with internal screw thread are watertight thanks to a silicone seal. A writing area makes it possible to identify the tubes. The caps are coloured in the mass to facilitate the identification of series of tubes.