Grizzly Mountain Flannel Shirt Jacket Men's Large Red Sherpa Lined Plaid Snap button closure.
Sleeves are insulated with a quilted lining.  Following measurements were taken on the inside of the garment to account for the sherpa cotton lining.

Underarm to underarm is 22.25 inches.  Sleeve length is 25.25 inches.
Center back length measures 30 inches.