This was first developed for the Industrial Vest.. while the men were cleaning out oil tankers in Louisiana .Conditions were 100% humidity , 100-120 F,wearing a self breathing device in a hazmat suit. It is 20-22" long and contains 2 #1 phase change cold packs. These will maintain a temperature of 58F, so no freezer burn! We have found them to last 2-3 hours, depending on heat conditions. We added bright color options..royal blue and true red. We designed them for people, but we know you are going to put them on your dog.I like them better as they are loose on me, and create a cooling effect all aroung my head and chest area.