Comfortably holds 5 Mapex 900 heavy boom stands, hi-hat stand, snare stand and base for stool. It's too narrow/shallow to actually fit a stool in though.
The side and top handles make it easy to lift in and out of the car boot (with a bandmate - it is HEAVY).
It is expensive, but then again, still cheaper than each of the stands it's keeping safe and a whole lot easier than making 8 trips from the car to venue...