This Corning cryogenic vial cap insert is made out of polypropylene. The assorted colors provide color-coding for easy sample identification. Packaged in resealable bags of 100 of each in white, blue, red, green, and yellow. Non-sterile cap insert fits all Corning cryogenic vials except Corning Item Number 430289. Non-Sterile. Material: Polypropylene. Color: Assorted White, Blue, Red, Green, And Yellow. 50/Pack. Corning #: 430499.