It's actually not a " duffle bag "
It's what's called a " pilots bag " and I have to agree those things are fan-fuckin-tastic I have two of them, one I use for misc. minion gear the other I have set up as my " build a home " bag everything under the sun that would help make life in a long term SHTF situation comfortable. Hatchet, air mattress, pump for said air mattress, another small tent for gear or additional people, tarps, blankets, stoves, propane, portable shitter and solar shower, ) stuff like that.
They are massive even though they don't look it. They work great the zipper is massive and the entire thing is like quadruple stitched. If you can find these things use them over the regular duffle bags cause duffle bags ain got shit on these pilots bags.