The foam in the bottom/back is cut to hold up to four pistols. You can pull the inserts out, put a pistol in that spot (for the range trip), then put the insert back in when your remove the handgun after returning home. Not sure if the whole piece of foam can be removed.
A really big pistol, like a TS, won't fit in the slots in the foam. Works fine for the standard full sized CZ's and compacts. It also has mag pouches inside some of the zipper pockets.