Nalgene 5012 Sterile Polypropylene Cryogenic Vials with Screw Caps are for storage in mechanical and vapor-phase liquid nitrogen freezers, at temperatures from –80 to 121°C. Sealing ring, in conjunction with specially designed threads, permits secure closure in approximately 2-1/2 turns. Thread position — internal for screw-cap, external for vial — greatly reduces risk of contaminating vial contents. Deep-skirted closure allows single-handed aseptic technique without exposing fingers to vial contents. Bulk packed 1000/case for economical purchase.