Originally Posted by jcinadr
The ball valve gives you an easy way to fine tune the amount of draft - and due to the nature of the handle - it is fairly easy to reproduce. You only need one valve (and two caps) to create any fraction of flow between 0-3 open holes.
That said, magnets work the same as caps, plus you can crack open a hole with one (fully adjustable). It is just not quite as easy to adjust and reproduce as the valve.
Exposed piping is to get the valve higher so you don't have to bend over.
I use my foot instead of bending over