1.Size : S:35*30*14, M:40*35*17, Suitable for cats and dogs within 4-8 kg back length(must measure your pets length and weigh together for accurate reference), taking each measurement a bit loosely will be more reasonably. 2.Durable and Comfortable Material: Made from breathable mesh and polyester fibre, lightweight and Comfortable, great ideal for outdoor trips, sightseeing, camping hiking and etc. 3.Adjustable Straps and Interior Drawstring: Adjustable padded straps help to reduce the burden. extra waist strap with buckle keeps the backpack stable. Interior rope with clip can connect to your pet's collar/harness to prevents your pet from jumping out or hurt itself.keeps them more secure. 4.Padding Panels and Removable Bottom Cover: With EPE foam padded back and sides, reducing the burden and offering more comfort to you and your pet, this rucksack/knapsack help your pet enjoy a nice nap/trip. Removable sturdy bottom cover makes it easier to replacement/clean. 5.Peep Hole and Mesh Pockets Design: A drawstring opening neck hole on the top of the backpack to keep your pet stick their head out, make them ventilation and visible, enjoy the entertainment with their host, adjustable hole string and soft mesh padded hole edge to ensure its security and comfort.Mesh side and front pockets help store leash, whistle, water, snacks, treats and other necessities.