Happy Puppy Designer Dog Accessory - Green Camouflage Harness and Poo Bag Set - Color: Green, Size: S For sizing chart, click on the other images link above. Sizing for each dog is unique. Similar to our clothing and accessory, medium size from one designer is not the same for another. For example our 9-pound yorkie model usually fits either one of three sizes (i.e. XS, S, M) depending on the designer. We highly recommend you measure your pet precisely with a flexible tape measure to ensure the best fit. Contact us if you have question. We are happy to help. Harness vests are comfortable alternative to collars for small pets as they evenly distribute restraint across the chest Features a sturdy D-ring for easy lead attachment Comes complete with a matching lead and poo bag