TPP cryo tubes made of polypropylene (PP) with external thread and star foot are designed for storage of biological material and samples down to -196C The screw caps with external thread reduce the risk of contamination and cross-contamination During storage build up of stress on the product can happen The TPP design as well as the high grade material ensures safe handling during and after the unfreezing process Features of the cryo tubes: With the geometry of the external thread TPP can abstain from using a silicone gasket, enabling the secure and tight closure of the tube The external threading results in a smooth internal surface that eliminates undue loss of specimen material during removal Colour-coding inserts in a range of colours offer a convenient marking and identification Supplied in convenient, puncture and tear resistant re-closable bags with zipper and laser perforation Self-standing Star foot Graduated with large writing surface Locking system: A single-handed operation is possible using the TPP cryo tubes with the cryogenic rack # 99016 with its locking system in the grooves Laser perforation: The laser perforation eases the first opening of the bag; no auxiliary opening aids are required. In addition an intact laser perforation functions as security seal Zipper: The re-closable mechanism of the zipper enables an easy, multiple opening and closing of the bag This makes sense with bags with large contents Filling Volume It is important, that the Cryo tubes are not filled up to the maximal possible filling volume. This is so the cell suspension has the possibility to expand during the freezing process (recom: 0.2 ml less than max. graduation of the tubes)