Hurtta Trail Pack Dog Backpack NO TWO DOGS ARE THE SAME - Dont guess on the size. Use the size chart along with the Measuring Your Dog size guide. The chest measurement is the most important for harnesses ADJUSTABLE - Adjustable belt, collar and chest strap to ensure reliable fit and prevent the backpack from shifting while your dog is moving CONVERTIBLE - The bag can be separated from the harness making it easy to load and easy to remove during breaks FEATURES  Waterproof zippers to keep contents dry and a handle on the top gives you more control over your dog in emergencies VISIBILITY - Efficient 3M reflectors improve visibility in low light situations