LARGE coming soon!
SMALL: 100 - 136 pounds, 30 - 36 above chest, 22 - 24 inch shoulder to hip (measure from top of shoulder to opposite hip bone). Possible body types: short to average height and build (5'2" - 5'6"), tall but thin and with narrow or sloping shoulders.
SMALL/MEDIUM: If you are in between size small and medium.
MEDIUM: 125 - 170 pounds, 35 - 40 inch above chest, 23 - 25 inch shoulder to hip (meausre from top of shoulder to opposite hip bone). Possible body types: average height and build, tall but thin and with long torso and broader shoulders, short but heavier set
We have found that weight and the above the chest measurement matters more than anything when sizing. | 
Sizing