Insulating box, 0°C cold pack, -21°C cold pack, rack plus lid. Modular system for transporting, storing, and gently thawing deep-frozen samples. Holds 24 tubes (0.5ml, 1.5ml, 2ml). IsoPack (cold pack) white for 0°C and blue for -21°C, for pre-cooling in the freezer. IsoTherm cooling times from = 6 hrs. (0°C, white) and = 3 hrs. (-21°C, blue). No more melting ice baths (contamination risk). All system components can be used separately. Racks can be stacked, are autoclavable, float in water and can be centrifuged in a microtitration plate rotor.