Without the insert bag is basic too small to place a 5D Mark III with an objective type Tamron 24-70 VC, so I use it only as a daypack.
The insert and the walls are fully reversible and velcro can be attached to any surface.
I did the test with my wife 700D with 18-135 mounted all installed STM lens at the bottom, the housing exceeds 4cm.
As against it fits perfectly inserted on the side with the lens attached or not (with that goal, I advise to disassemble to optimize storage)