“Size M”: 10.6''(L) x 6.3''(W) x 13.0''(H), your pet's BACK LENGTH should be between 12.0''-14.0''; Recommended WEIGHT of “3kg” maximum. Please MEASURE your pet's length and WEIGH for accurate reference. "DURABLE & BREATHABLE MATERIAL": Made from BREATHABLE MESH and POLYESTER fiber, lightweight, flexible and comfortable; DURABLE and strain resistant, SAFE enough to bear the burden. “SAFETY GUARDED”: The interior ROPE with CLIP can connect to your pet's COLLAR/ HARNESS to prevent your pet from jumping or getting hurt, which keeps them safe. “PADDED Shoulder Strap, FIRM Support”: adjustable padded straps to reduce load; Extra waist strap with buckle to keep the backpack stable; CONVENIENT SIDE POCKETS to store leash, whistle, water, snacks, treats and other NECESSITIES. "COMFORTABLE" - Front hole is ADJUSTABLE with drawstring according to size of your pet. Well-VENTILATED design for optimal airflow and pet checking, soft and comfortable lining for your pet to relax and rest.