I think it's about 24 Liters.

I just returned from a factory that makes a huge range of these boxes in Wenzhou and I think Carl has covered most of the bases with that sweet product review . The boxes with the dull textured finish like CCs' are Polypro plastic and the shiny painted ones are usually ABS so they are a little more brittle. For what you pay, I think they are a good bargain.

One bit of advice... if you are hammering the shit out of the bike, throw a bungee over the thing just to be safe. These boxes are only load rated for about 3-4 kilos which is pretty easy to go over if you're packing for a long trip. I had about 12 kilos in mine when I watched it go tumbling behind me at 80kph after 5000 kilometers of abuse. Thing was seriously road-rashed but never came apart so I'm not complaining.

Cheers!
ChinaV