ThunderShirt's patented design applies a gentle, constant pressure that has a dramatic calming effect for over 80% of dogs. Most effective anxiety solution as voted by veterinarians Already helping hundreds of thousands of dogs and cats across the country Great for storms, separation, travel and many other anxieties No need for training or medication. How It Works Thundershirt applies gentle, constant pressure on a dog's torso, and this pressure has an amazing calming effect for most dogs. Use Thundershirt for Fear of Thunder Barking Problems General Training Tool Any Noise Anxiety Separation Anxiety Car or Travel Anxiety Any Excitability Crate Anxiety Reactivity General Fearfulness Leash Pulling Selecting a Size SIZE CHEST SIZE WEIGHT (Kg) XXS 9" up to 13" 50