The valve is a prototype, an all aluminium high pressure version is soon to come in the future. By high pressure I mean around 800-1200psi, not difficult to do at all. It will be machined out of series 6800 aluminium, thats what is available and is very close to series 7000.
Anyway, enough of that. I can't really give away any specs, if I were to describe it I would say something close to a mechanically operated piston valve.
I will give you a pic and a video, the cannon itself is quite small, it has a 32mm barrel and a 40mm chamber. I have only tested it today at low pressure with toilet paper as the projectile. Which you can imagine doesn't yeild the best prefomance. But it works, and thats all I was aiming for.
There is some more developement to do here but the concept is looking good.

