Everyone knows that Crumpler sizes are a joke, but the bag is well made and is still looking as good as new a couple of years later.
In this bag I can fit a D-SLR (D300) with walk-about zoom (16-85 VR) and a second large lens (80-400 VR), or a pair of flashguns in place of the large lens (SB-800 and SB600).
In the outer pocket I can fit a couple of spare camera batteries and lots of memory cards.
And I can walk around with this kit for about 4 hours before it feels heavy, in 32 deg C and high humidity!