Charts fit great in the middle (which has a adjustible divider), as would a knee board if your into those things
Haven't had much get lost, know where everything is by feel and not much moves.
I keep a GPS, NAV/COM, pen, lead holder, ruler, protractor, e6b, poh, note pad, surefire flash light, extra AAs, leatherman and benchmade knife, sectional, WAC, terminal and a few plates, pass port, deck of cards for weather, used to carry my old logbook (new one is digital), head set adapter for nav/com. 12v adapter for gps charger. In the backcountry I could also fit my 5" 2011 pistol.
It still has room to spare.