I got a medium black bag, and it's still fairly big. I use it for school and keep about 3-4 books in it plus a binder and it could definitely hold more. The first night I got it I bought $200 worth of clothes at the mall and rode home with it all in my bag, stopped at best buy and bought some ipod stuff and that went in there as well with 1 u-lock and 2 cables. The strap design they use is genius, it tightens and releases so easily, although the buckle was an eyesore at first it adds some character to the bag like the seatbelt buckle to chrome. Fits extremely well and was a very solidly-stitched bag, I'm extremely happy with it.