The medium to extra large sizes of Canine Quick Wrap, take two #2 cold packs. The small take one #1 cold pack. Turn the garment to the mesh side, and open the pocket. One cold pack goes into each side in the bottom of the garment. Below is a photo.You can install before you freeze the packs, or install after they are frozen. I like to break the frozen pack, so I can curve it to the dogs' body. If you freeze the complete unit, you will get a little more cooling capacity from the precooled phase change material, in addition to the cold packs.