If you need a way to keep your food cold or frozen, these blocks of rigid foam will do the job for up to 2-3 days. They are reuseable, non-toxic, and rated the best in foam refrigerants. They prevent thawing or keep frozen foods chilled for an extended period of time. You can also use them to protect against freezing. When packaged in properly insulated containers, warmed RE-FREEZ-R-BRIX® release heat, keeping perishables from freezing. They will also protect from warming. Keeps perishables requiring a temperature range of 32° F to 60° F at a safe, uniform cool temperature for several days. Freezer packs or gel packs are a less expensive option, but they do not stay cold as long as the bricks. Our ICE-BRIX® are gel packs that are sealed in heavy duty plastic. They will also help keep perishable products at a constant temperature for a shorter time period of hours to 1-2 days. It is important that in order for any of these products to work properly, they have to be used in conjunction with a insulated container, such as EPS foam inserts or insulated mailers.