These specially formulated Simport Cryovials Premium Polypropylene Vials And Caps are designed for bio-storage at temperatures as low as -196°C, but should only be used in the gas phase of liquid nitrogen. Super fast thread removes cap in 1 1/4 turns. Cap also features exclusive silicone seal to ensure a positive closure at even the lowest cryogenic temperature. Closure and vials are both manufactured of polypropylene with the same coefficient of expansion, ensuring an equally secure seal both at room temperature and at low cryogenic temperatures. Tubes can be easily identified using the white marking area and can be color coded with cap inserts, available separately. Vials are radiation sterilized and packed in a tamper-evident, resealable safety-lock bag of 100 and are also certified DNAase/DNA/RNase- and pyrogen-free. Autoclavable.