Topeak calls this a portable tune-up stand. It's like one of those bottom bracket supports that you used to be able to buy - the ones that look like a coat-hanger done by Dali.
A hook goes over the down-tube, the bottom bracket rests on the middle of the stand, and the rear wheel is held a couple of inches off the ground. Since you can turn the cranks, it's fine for adjusting your gears or rear brake, and fixie riders can use it to sort wheel alignment. In fact, it isn't like one of those stands - it is one of those stands. The difference is that, as it's from Topeak, it also folds up. It's a tune-up stand in disguise, a kind of Optimus sub- Prime. When folded, it measures 20x8x4.5cm. When unfolded, you can set the hook height for 26in or 700C wheels. There are rubber bits to protect your bike's paintwork and the hook is wide enough for any round or oval down-tube, though it won't do some suspension frames or folding bikes. It's obviously not as good as a proper stand but it could come in handy if you need to tweak your gears before a race. Its potential flaw is that it folds, which makes it more packable but less sturdy.