Designed for the storage and transportation of biological material. Manufactured from non-toxic polypropylene, the tube cap fits the  external thread vial T501 range. Tubes and caps can be autoclaved (121 °C) in upright position with caps loosened. Caps have a internal seal that seals into the inside of the tube on closing, ensuring a leakproof airtight seal. Both tube and cap is made of the same material and thus have the same thermal expansion insuring a good seal at all temperatures.Color coding inserts for the caps  are also available and makes sample identification and grouping easier T312 range