◎ Suyi Medical cryotube is made of Medical grade PP material, It is the ideal lab consumable for biological sample storage. In the gas situation of liquid nitrogen, it can withstand temperature as low as -196 ℃.Silicone gel O-ring in the cap ensures no leakage, even in the standard lowest storing temperature, which will guarantee the sample safety. Different inserted color top will help easy identification. White writing area and clear graduation make the mark and volume calibration more convenient. ◎ Cryotube with external screw cap is designed for freezing samples,The external screw cap design can reduce the contamination probability during sample treatment. ◎ Cryotube with internal screw cap is for freezing samples in gas situation of liquid nitrogen. The silicone gel o-ring can enhance the sealing performance of the tube. ◎ The caps and tubes are all made of PP material with same batch and mode. Thus same dilatation coefficient can ensure the tube sealing performance under any temperature.