Shells material:Liner:breathable air-mesh. The metal clip makes it easy to adjust size around pet’s chest.Easy to get on and off. Detailed design,elegant and classic pattern,bow-tie element gives your pet a smart look Please mainly relying on your pet’s chest girth when choosing the size,weight is just a reference point.Size S:Chest Girth 9"-13" Weight Reference 3-6.5lbs. PLEASE REFER THE SIZE CHART TO SELECT THE CORRECT SIZE FOR YOUR PET.