XS
Pit to pit: 19".
Length of back: 24".
S
Pit to pit: 21".
Length of back: 26".
M
Pit to pit: 22".
Length of back: 28".
L
Pit to pit: 23".
Length of back: 28".
XL
Pit to pit: 24".
Length of back: 29".
XXL
Pit to pit: 25".
Length of back: 30".