I had one about a yr back, sounds the same where you simply twist the pole to turn flow on or off.
Mine must have been mark1 as it didnt seem to last overly long.
However it may have been my fault. It used slug screws (if thats what their called?) to tighten it. As i sometimes work with the brush vertical it kept switch itself off and so i was forever tightening it up and then i think i must have over tightened (which was easy to do) as it simply busted it and that was that.
However the concept of it and when it worked, i did enjoy its use.