XS is suitable for 2.5-3.5kg; bust 30-34CM S suitable for 3.5-5kg; bust 34-40CM M is suitable for 5-6.5kg; bust 40-45CM L is suitable for 6.5-8.5kg; bust 42-48CM COMFORTABLE AND SAFE - Made with a soft, breathable air mesh, ultrathin, and super breathable and more comfortable, this lightweight pet harness is perfect for walks in hot summer. The vest-style design disperses the pressure through shoulders and chest, uniform force, no need to worry about the danger of suffocation or choking.Our hook and loop fastener, buckle and D-rings work together protect your pet in three layers of security. REFLECTIVE DESIGH - With premium reflective strips and four reflective bands on the sides, this harness can be seen even in low visibility conditions or dark night, making it easier to control dogs and ensuring the safety of walking at night.