The bag is like a bag inside a bag - all of the inner pockets for your phone and zippy compartments are in an additional pouch which you can also remove if you like. It makes the bag really room as you can put things in the pouch and have it all safely zipped up, as well as put other things down the sides - for me it's usually my comfy flat shoes!
I actually bought this on ebay a few months ago and the only listings were in Hong Kong, so it took a few weeks to arrive. I've now found a listing that's slightly cheaper than what I paid and it's a UK listing, so all the better. You can get the bag here for £16.55 and it also comes in black.