Designed for Small Pets --- The method of measurement is shown in figure 2.The dog carrier bag is designed with Ventilation Mesh, Elastic CHEST Straps,Adjustable Shoulder Strap/Waist Strap,Tail Hole,Smooth Zipper.This dog backpack is not only great for hiking (to carry him when he gets tired),it's also been super useful for taking him around townPlease DO measure your pets and choose according to the size chart (fig.2). Hand Free --- This front carrier provides an exceptional comfort for your pet! it keeps your pet safe & close to you, easier to take care of him/her and while giving you hands-free mobility. Designed for pets weighing up to 4-22 pounds Considerate Detail-oriented Design --- Legs-out and tail-out design keep your pet safe and comfortable; Hook and loop, zipper and elastic openings allow you to fit your dog inside comfortably; Quick Release Buckles on the end of straps ensure quick installation with just one hand. Enjoy the Time with Your Pet --- The pet carrier backpack is convenient and lightweight, you can use it to carry dog or cat when you are hiking, biking, walking, camping, traveling or other outdoor activities, which is a useful bag to free your hands while carrying a pet. It also provides interesting backgrounds for photos. Secure & Convenient Pet Travel Backpack --- The legs & tails out design keeps your pet protected, and comfortable; you can carry your pets just like an infant on your front or back while keeping your hands free; and they'll looks super cute, perfect for shopping, hiking, cycling, and other outdoor activities.