【Large Space and Sturdy Frame】The approximate size of this pet backpack carrier is 13"Lx11"Wx16.5"H, the fully expanded size is 13"Lx23"Wx16.5"H, large space can accommodate a small medium cat or dog up to 20 lbs. The built-in metal frame makes the backpack structure more solid and will not deform or collapse. it is comfortable for you and your pet while traveling, hiking, attending a pet party or going for a walk in the park, or taking your pet to the vet and other outdoor use. 【Double Safety Guarantee】All the zippers are equipped with locks except for pockets. After you locked the zipper, pets can't pull the zipper away themselves, which can effectively prevent pets from jumping out. There is also a safety strap inside the backpack, when you want to open the top window to let your pets stick their head out, just connected the safety strap to your pet collar, it can prevent pets from falling down. 【Breathable and Comfortable】Petskd pet backpack is designed with 3-sided mesh windows to ensure breathability, through these mesh windows, your pet can maintain good ventilation and see the scenery outside easily. If you open the top mesh window of the backpack, your pet will have more space to interact with the outside world. The backpack also has a two-way entrance for easy access to your pet.