Size Gide: 5 models, suitable for cats, puppy, small and medium-sized dogs. For your pet's best fit, please carefully measure the size before purchg. Size:XS: Neck 8.66-10.23" Chest 11.02-11.81"?S: Neck 11.02-12.6" Chest 13.78-14.96"?M: Neck 13.38-15.35 Chest 16.14-17.32"?L: Neck 13.78-15.75" Chest 17.72-18.9"?XL: Neck 17.32-18.9" Chest 21.65-23.23". Reflective Design: With reflective strip design and 1.25m reflective dog leash, the reflective small dog harness and lead set is visible in low light conditions, Improves safety when walking at night. Easy to Put On & Adjust: This adjustable step in harness for cat and dog is One-piece version, easy to put on and off with back buckle and velcro. Velcro can easily adjust the size, which allow a just-right fit for your cat and puppy. Breathable & Lightweight: This puppy padded harness for small dogs constructed with the honeycomb ventilation mesh design. The material is soft and does not hurt the dog's fur. It is more comfortable and breathable in summer, allows efficient air flow throughout the chest area to keep the dog cool and dry at all times, dog and cat harness is suitable for daily walking, jogging, training, etc. Safety & Comfortable: Puppy harness with Sturdy buckle and D-ring on the back connected to leash, rotating hooks made of aluminum, safe and stable. The vest design of this dog harness small dog distributes the belt pressure evenly over the chest and shoulders to avoid suffocation or neck strain.