I haven't used them, but I just looked them up on ebay. The most useful parts seem to be the thingies to balance them (the tubular items of which there are three present). I can't really tell if these are some kind of gauge or just a fancy tube. If they are gauges then it seems like a reasonable deal. There are also other items on the market that serve the same function, I've seen similar gauges/gizmos from Snap-on, Midlock and Gunson at least. They're essentially a vacuum gauge you place over the carb while you adjust the carbs to give identical readings. Otherwise all the tools you need for an SU carb can be found in a normal toolbox; they're not particularly complicated.

Bram