Mountain Hardware Fluid 26 Backpack Size Chart
  Small/Med Med/Large
Torso Fit Range (in) 16-19" 18½-22"
Capacity (cubic in) 1585 1700
Product Weight 1 lb, 11 oz 1 lb, 13 oz

These are general guidelines only, sizes are not guaranteed. But no worries, since at SunnySports we offer our exclusive PFF Guaranty