ZippyPaws Adventure Backpack is designed for carrying water, food, and other essentials on day hikes and short trips. Lightweight and breathable fabric keeps dogs cool on the trails. Roomy dual pockets distribute load weight evenly. Reflective trims keep dogs visible in low-light conditions. It is recommended to keep dog's load below 25% of their body weight. Medium (ZP520): 21 - 27" in girth X-Large (ZP522): 33 - 40" in girth