CryoKING 5.0 mL Cryovials, External Thread, Blue Caps Assembled by Biologix are sterile polypropylene vials for storing larger aliquots of serum, plasma, cells and tissue. The external thread is o-ring free to reduce contamination, the blue caps support color coding, and the vials have no barcode. Packed 25 per bag, 1000 vials per case.