The Pet Life ® 'Waggler Hobbler' Large-Pocketed Animated Fashion Dog Harness Backpack features an expressive Penguin-faced animation that's both fun and functional. This dog backpack features a large spacious zippered usable back pocket that is perfect for placing belongings. Exo-shell is composed of durable Nylon that is reversed with comfortable Micro-mesh for complete breath-ability and comfort that gently hugs the body. The back of these dog harnesses features a ring and dual buckles made of durable seat belt-like heavy duty Nylon that connect to any and all dog leashes. Available in Multiple Sizes. SIZING MEASUREMENTS - (In Inches) SMALL - Length - 5.51" Chest Girth - 14.9 - 17.3" (Smaller sized breeds) MEDIUM - Length - 7.08" Chest Girth - 18.1 - 22" (Small to Medium sized breeds)