Alkali Scientific's 2mL Test Tubes are made from premium A+ Grade pure polypropylene. This A+ Grade polymer gives the tubes extremely clear appearance and smooth surface making them naturally low-retention. The caps on the A+MicroTubes are slightly larger than most brands with a rounded underside making them much easier and more comfortable to open/close. They are 'thumb-friendly'.

With that being said, the A+MicroTubes have a very secure seal. Just feel for the comforting 'snap' when you close them and, rest assured, you need not to worry about leakage and/or evaporation. They can boil and freeze and you can probably run them over with a truck. Finally, a microcentrifuge tube that has it all.