Pack sizing. Personally I'm short at 5 1/2 feet. Short legs average torso overweight. My torso is 19+ inches and I use a regular size pack with men's straps and belt. Small is too short to be comfortable, I have tried them. GG will swap out sizes on unused belts and straps for free.
From the GG website,
Short Torso = 15-18inches
Regular Torso = 18-21inches
Long Torso = 21-24inches
CCS is not as flexible in sizing.
butthead