X-Small - Head/Neck 8” - 12.5” Stomach 10” - 15” For Dogs between 2 - 7 lbs

Small - Head/Neck 9.5" - 15.5" Stomach 12.5" - 18.5" For Dogs between 4 - 17 lbs

Medium - Head/Neck 12.5" - 22" Stomach 16.5" - 27.5" For Dogs between 15 - 35 lbs

Large - 25mm Webbing - Head/Neck 19" - 31" Stomach 24" - 38" For Dogs between 35 - 100 lbs