Techni Ice reusable dry ice packs/gel packs start as a flat sheet and absorb water through a special perforation technology in the surface of the product. This is achieved by scrunching the sheets between your hands whilst immersed in warm water for a few minutes until the air bubbles have escaped. The hydration process then begins and the cells will swell which means it's ready to be used. The water enters through the surface and activates the polymer which then swells the sheet into 24 individually sealed cells and can be frozen and cut to size. Techni Ice reusable dry ice packs/gel packs can be used hot, cold, or frozen. It can also be used in 12-volt fridge/freezers to reduce the cost of keeping them cold.