Vials are free standing with a conical bottom and feature 0.5 ml graduations. Designed for use in the vapor phase of liquid nitrogen and are ideal for storage or transport of material at extremely low temperatures. External threads provide a smooth inner surface. The screw cap incorporates a molded-in sealing ring for a tight, leakproof seal. Smooth Skirt Cryogenic Vials have printed graduations and smooth inner walls for easy filling and sample preparation. Printed writing area on side for permanent coding. Vials are molded from polypropylene and are freezable to -70°C. Sterilized by gamma radiation for immediate use.