The main padded back panel is approximately 11" by 17"
There is a soft "open cell" foam pad under the back panel mesh, and a super stiff but flexible "foam board" as a frame sheet, inside an inner "pocket". Its not easy to remove the frame sheet, but it can be done.
Like all "surplus", it had that "long term storage" funk.
Given its budget price, I simply pulled the stiff frame sheet out, separated the pack into 3 parts, and washed in a front loader washing machine with a 1/4 of bleach. Do this at your own risk.
Theres a small tag sewn on it inside, that says it was sewn in Vietnam.
It is not USA surplus, so expecting it to be Berry Compliant is a bit much.
Fully expanded, the pack is almost 11" deep at the top and measures approx 9" deep at the bottom
You could unzip (sides) and unsnap (bottom) the main pack back and have a "radio pack board". the 3 compression straps on each side are actually properly designed so that the pack board would still have 3 "compression" / load straps.
The DPM fabric is kinda "plasticky" and stiff, but its functional
Top pocket is retained by 3 Fastex buckles.
There are lift/carry loops on the back panel side as well as the pack bag side so it can be readily picked up like a grocery bag, tho the top lid can get in the way depending on how its packed.
Theres a 7" tall extension sleeve on the main pack bag to corral over loaded gear.
Theres some extra D rings, tri glides and fastex clips on the pack, presumably for accessory pockets or…