Interior of the HP has plenty of room for my 50 / 24-105 L attached, and 70-200 f4.0 L IS (or my 70-300 DO IS) placed vertically.
There is also room for the camera with either of these longer lenses attached. Plenty of room on top or under the camera for smaller items.
I put two of the included velcro dividers here just to show them. They come apart and velcro in wherever you want them.
The entire insert is removable. The inserts are also sold separately so that you can configure them for another camera set-up,
and just lift out and replace the whole liner and not have to rip out all the dividers and start over .

There are also two bellows pockets in the front of the bag that snap shut, and a full width zipper on the back for flat items like manual, air tickets, etc.