@Ski169 what backpack is that? How did you attach the buckles to the Molle?
That is the Tactical Tailor Removable Operator Pack. It comes with a set of buckles for attaching it to a plate carrier, other packs, or anything that has MOLLE webbing. I had it on my Tactical Tailor Extended Range Operator Pack but need to buy a second set of buckles (which they sell separately). The top buckles use their Malice Clips for weaving through the webbing and the bottom clips hook onto the webbing. It's pretty secure. I would think the stitching would rip first. In the event I have to abandon the truck, I always have a pack to take what I need. It's a little smaller than a 3 day pack.
Removable Operator Pack