Drag bags are fairly a fairly recent thing. A good back pack will carry almost everything you need. Drag bags are just extra baggage ( pun intended ) when you have to move fast and stay low. This does happen quite often. If you must use one, then: personalize to suit you needs. Perhaps a spotter scope, spare rifle optics, in case the mounted one get damaged, some people use range finders, snacks ( it could be a long watch) an e-tool and tp, again, it could be a long watch etc.. You're only limited by how much you are willing to carry and what will actually fit inside the bag.