Pack of 500 externally threaded cryogenic vials with 4.5ml capacity and star-shaped base. Designed for storage of samples as low as -196°C*. Manufactured from polypropylene. Feature a large white frosted labeling area, silk screen graduations, and a leak-proof HDPE cap. Vials have an internal U-shaped bottom. Self-standing star base vials are designed for one-handed use with a support rack. DNase, RNase, and Pyrogen-free. Radiation sterilized. *Not recommended for use in the liquid phase of liquid nitrogen. Can be used in vapor phase of liquid nitrogen.