The warm and stylish puffer vest with a stretch belly panel, Why you'll love the Summit Stretch Vest Water-resistant exterior so your pup can stay protected Soft fleece lining & faux-down insulation for ultimate warmth Stretch belly panel for an adjustable fit BACK LENGTH Measure from the base of your dogs neck (right below where their collar would sit) all the way to just above the top of their tail. CHEST GIRTH Measure around the largest part of your dogs chest, just behind their forelimbs. Size Back Length Chest Girth 10 10" Up To 18" 12 12" Up To 20" 14 14" Up To 22" 16 16" Up To 25" 18 18" Up To 27" 20 20" Up To 29" 22 22" Up To 30" 24 24" Up To 32" 26 26" Up To 34" 28 28" Up To 38"