Is the TECHNI-VALVE No. TV-101-A the valve that is supposed to be discontinued.
http://www.pecaproducts.com/trigger_valves.htm
It sure does show a strong resemblance to the power trigger valve from Usher. Looks like the same valve but modified in that the nozzle was cut back and an adapter fitted. Without being able to see a pic of the underside of the TV-101-A, the power trigger from Usher may have also had a machined brass adapter that pierces the opening in the powermax vessel. Looks like a knurled nut was also adapted to tighten down on the three prong clamp.
To much of a coincidence for this not to be the same valve. Now whether that particular trigger valve is available any longer or not remains to be seen. I'm sure someone out there is sitting on a stash of them.