SIZE - SMALL : Neck Girth: 12-18” , Chest Girth: 14-24”. Very Important to Measure Before Buying. When it properly, two fingers should barely between the fur and strap. EASY TO PUT ON AND TAKE OFF: This soft mesh dog harness is easy to put on and take off with its 2 quick-release buckles. Just slide the harness over dog's head, buckle it up, adjust the straps! REFLECTIVE STRAPS FOR SAFETY: The reflective stitching will be really nice and high visibility when it gets dark. Your dog will be seen easily. This reflective material can make drivers have long time to react, which ensure your dog’s safety.