Flowt Pet Life Vest SM: 8-15 lbs.; Neck Size 10"-13"; Chest Size 18"-24"; Waist Size 14"-20" MED: 15-30 lbs.; Neck Size 12"-16"; Chest Size 22"-28"; Waist Size 18"-24" L: 30-60 lbs.; Neck Size 15"-19"; Chest Size 26"-32"; Waist Size 22"-28" XL: 60-80 lbs.; Neck Size 18"-22"; Chest Size 30"-38"; Waist Size 26"-32" 2X: 80+ lbs.; Neck Size 18"-24"; Chest Size 30"-42"; Waist Size 26"-36"