S                 M                L                 XL                2XL
full body length  10"               12"          15.5"            17.5"               20"
neck opening       4"                 4.75"       7.75"            8.75"              9.5"
sleeve length       4"                 4"             5.5"              6.5"               7.5"
chest width          7.25"             8.25"       9.25"           11.5"            12.75"
weight           up to 10 lbs    12-25 lbs    26-40 lbs     41-60 lbs     61-80 lbs

Fits on the small side.