Features & details BOTH YOU AND YOUR PETS ARE SATISFIED WITH THIS BACKAPACK: This cat/small dog backpack measures 13.8x10.6x16.9 inches when unexpanded, providing your pet with big space even without pulling out the expansion area, and the expansion area can be pulled out when resting, allowing your pet to enjoy a outdoor tent. The wide and pressure-resistant straps and back are designed to make your pet and you both comfortable for outdoor travel. EXPANDABLE AND COLLAPSIBLE CAT BACKPACK CARRIER: This PETKIT pet backpack has an expandable back, which allows your pet to walk around comfortably and reduce anxiety. And when not in use, the backpack can be folded for storage. MAXIMUM AIR CIRCULATION AND MULTIPLE ENTRANCES: 4 mesh windows provide optimal air circulation for your pets, spacious front entrances and side entrances make it easy to get in and out even for larger cats. The backpack also comes with a two-side pad for winter/summer use, and storage pockets on the backpack are details we've thought of for you. SUN PROTECTION ROLL-UP CURTAIN: The door curtain of this cat travel backpack can be rolled up or down, When sun is strong,it can keep your pet out of direct sunlight. It's perfect for taking your pet along on trips, camping, biking, trips to the vet or walks in the park. STURDY AND SAFE: PETKIT cat dog bag is made of high quality fabric, it is not easily scratched, strong and durable, while this material is also soft for pets