KolBoy GelPaks are filled with white granules made of a superabsorbent polymer refrigerant (SAP) crystals. Six mil polybags insure that the crystals will not leak onto valuable products. When water is added (SAP) will absorb 125 times its weight in water. After freezing, two pounds of Gel absorbs 36,000 calories of heat energy upon phase change from ice back to gel. KolBoy GelPaks may be refrozen and used again for certain applications. These may be supplied separatelsy with our thermal shippers to increase the interval that products remain cold.