[ DIMENSIONS OF PET BACKPACK ]: Before purchasing, please measure the dog's sitting height (from front legs to the top of the head) to ensure that the dog's sitting height is within the recommended range, otherwise it may be too large or too small; L size: 17.413.410.6in, suitable for cats less than 15.4lbs; for dogs less than 13lbs and sitting height ≤15.6"; XL size: 19.315.712.9in, for cats that 15.4lbs~24lbs; for dogs 13lbs~22lbs, and sitting height /15.6"~17.6".[ EXPANDABLE DESIGN ]: Expanded size: 13.4" L x 24.4" W x 17.3" H. This pet backpack with an expandable back design gives your pet more space to rest and increases air circulation, allowing your pet to move around more comfortably and reducing anxiety..[ GREAT VENTILATION & COMFORT ]: Comes with 4-side breathable mesh windows, giving plenty of air for pets. Makes it easy for you to observe the movement of your pets while they are enjoying the scenery outside. The pet backpack carrier multiple ways to let your pet in and out with ease. To enhance comfort, the pet cushion is placed inside the bag's bottom and has a removable, washable cover. This ensures your furry friend has a spot to rest while on the go..[ ERGONOMIC DESIGN ]: The widened & padded shoulder straps and back provide support and help reduce load and increase comfort. 2 retractable buckles on the top and bottom of the cat backpack to prevent shoulder strap deviation and maintain the stability of the dog carrier..[SAFETY & STORAGE ]: 1, Made of high-quality Oxford Cloth, waterproof, anti-scratch, and non-irritating, let your pet breathe ly and relax. 2, Adopts lock-type zippers design to prevent the zipper from being opened by pets. Built-in retractable hook rope to prevent pets from escaping. 3, The pockets on both sides can store food, poop bags, and some necessary accessories.