WorldPet Thera Cool Cool Pouch System + Bonus Cooling Pad (Small / Medium) Keep your dog cooler with Cool Pouch technology Compatible with harness: Chest 14 to 21 inch (35.56 to 55.88 cm) Compatible with collar: Neck 8 to 14 inches (20.32 cm to 35.56 cm) Non-toxic; Pet safe Cool Crystal technology; Radiant barrier