Color-code your vials. Thermo Scientific™ Nunc™ CryoTube™ colored caps are designed for use with Nunc internal screw-cap cryovials and come with a silicone gasket to ensure a perfect seal. Since the creation of the first cryovial in the early 1960s, Nunc CryoTube cryovials have been the most widely used cryovials in the world. Proven design, high levels of certification, and a broad portfolio of cryopreservation products provide researchers with a cryopreservation option that suits their application and gives them peace of mind, while keeping samples viable and undamaged.