The Pet Life EVEREST Backpack features authentic seat belt material straps and a DUPONT Heavy Duty Buckle to secure weight and Adjusts at the belly accordingly. Features a waterproof interior and zipper to seal off any and all liquids. The reflective strips on both sides are an important SAFETY component. Outerlined with high quality and breathable Mesh fabric where it gently hugs your pet’s body. Lightweight and Durable. The Zippered Pocket features room for any essentials. The Everest Backpack is also a Harness and features a Harness Ring that can attach to any Leash. Size SMALL Backpack fits all Teacup to Small Sized Breeds (8″ – 12 Inches From Neck to Tail). Size MEDIUM Backpack fits all Medium to Mid Size Breeds (13″ – 20″ Inches Form Neck to Tail)