CRYOVIAL, Internal Thread with Silicone Washer SealCRYOVIAL, Internal Thread with Silicone Washer Seal Designed for storing biological material, human or animal cells, at temperatures as low as 196C (but should be used only in the gas phase of liquid nitrogen). A silicone washer between cap and vial ensures a positive leakproof seal at all temperatures. A 1 1 4 turn of the cap is sufficient to seal the vial. Closure and vials are both manufactured of polypropylene with the same coefficient of