Liter volume is a useful label. It is not the whole packing decision. Two packs with the same stated capacity can fit different loads once the torso length, opening and pocket layout change.
Put dimensions next to the liter rating
Record the stated volume and the external dimensions together. Height, width and depth show whether the pack stays within a carry-on limit, a locker, or the space you have planned for retail display. Ask for the measurement method so every model is compared the same way.
Read the opening and the pockets
A top-loader, a panel opening and a roll-top give different access to the main compartment. List the pockets that matter for the range: hip-belt, lid, front shove-it, hydration sleeve or a separate base compartment. Note which pockets are stretch, zippered or open, because that changes what a buyer can reach without unpacking.
Check the carry points
Shoulder-strap attachment, hip belt, sternum strap, haul handle and lash points decide how the pack is carried and how it is hung or strapped to other gear. If the range includes a frame or a framesheet, say so separately from the fabric body.
Keep packed size distinct
The volume in use is not the packed size and not the carton size. Ask for the packed unit dimensions, the carry method, units per carton and carton dimensions before you compare freight or warehouse space.
