SIZING GUIDE 1.Please measure your dog's neck and chest girth with a soft measuring tape before purchasing. 2.If your growing dog fits two sizes listed,please choose the larger size. 3.Measuring the chest width at the broadest part of dog's chest. 4.Size information comes from manual measurement, and may exist error of 0.4-1.2inches. XS: NECK:28-30.5cm/ 11-12 in CHEST:29-33cm/11.4-13in S:NECK:33.5-36cm/13.2-14.2in CHEST:34-38cm/13.4-15in M:NECK:39-41.5cm/15.4-16.3in CHEST:39-44cm/15.4-17.3in L:NECK:44.5-47cm/17.5-18.5in CHEST:45-50cm/17.7-19.7in XL:NECK:50-52.5cm/19.7-20.7in CHEST:51-57cm/20-22.5in STEP1 1.Put on the harness through your pet’s front legs. STEP2 2.Pull the harness up, simply adjust strap on the Velcro closure, and dig out the D-ring. STEP3 3.Adjust strap on the Velcro closure,loose enough that you can fit 1-2 fingers between the harness and your baby. STEP4 4.Clip the leash to D-ring. Read more