The Compac Cool Packs are supplied with every medium, large, and XL thermal bag, where internal straps hold them securely in place. The Cool Packs are also available separately for those who want extra cooling or wish to replace an original one. They come in two sizes: standard, provided with the thermal bags, and XL, which fits into the bottom of the XL thermal bag. The Compac Cool Packs must be frozen for 24 hours before use to keep the contents of the thermal bag or Compac Cooler cool for as long as possible.