[ DIMENSIONS OF PET BACKPACK ]: Ensure the perfect fit for your pet by measuring their sitting height (from front legs to top of head) before purchasing. The sizes are as follows: - L Size: 17.4 x 13.4 x 10.6 inches, ideal for cats up to 15.4 lbs and dogs up to 13 lbs with a sitting height of ≤15.6 inches. - XL Size: 19.3 x 15.7 x 12.9 inches, suitable for cats weighing 15.4 to 24 lbs and dogs weighing 13 to 22 lbs with a sitting height of 15.6 to 17.6 inches. [ EXPANDABLE DESIGN ]: Expanded size: 13.4" L x 24.4" W x 17.3" H. The expandable back design provides your pet with additional space, enhancing comfort and reducing anxiety during travel. [ GREAT VENTILATION & COMFORT ]: Equipped with four breathable mesh windows, this backpack ensures optimal airflow for your pet. It allows you to monitor your pet easily while they enjoy the view. Entry and exit are made simple for your pet, and the included cushioned pad has a removable, washable cover for easy maintenance. [ ERGONOMIC DESIGN ]: The padded and widened shoulder straps distribute weight evenly, ensuring a comfortable carrying experience. Two retractable buckles help keep the straps secure and reduce slippage. [ SAFETY & STORAGE ]: Constructed from high-quality Oxford Cloth, this bag is waterproof, anti-scratch, and non-irritating. Lock-type zippers prevent accidental openings, and the built-in retractable hook-and-rope system secures your pet. Side pockets provide extra storage for food, waste bags, and other essentials. Use scenarios: - Perfect for hikes or outdoor adventures where your pet can comfortably observe their surroundings. - An ideal solution for trips to the vet, ensuring your pet feels secure and relaxed. - Great for traveling on public transportation, providing a safe and spacious environment for your pet.