According to Leisurepro.com
Q: How do I know what size to choose?
A: S-M = 32" to 46" waist, 5'2" to 5'9" height, 150 lbs to 185 lbs, 36" to 40" chest;
Large = 34" to 48" waist, 5'9" to 6'4" height, 185 lbs to 240 lbs, 40" to 50" chest;
XL = 40" to 54" waist, 6'4" to 7'0" height, 220...