Another aspect of this hobby I do not have much knowledge off - interesting looking device. That's the thing that dials down the pressure to Thomas
Yes, Thomas, the regulator brings the pressure down from the roughly 800 psi (it depends upon the temperature, actually) to a little under 150 psi. There are two places where Allen wrenches are used: the on/off uses a 2.5mm and the pressure adjustment uses a 5mm. The gauge measures the output pressure, as the input pressure is largely a function of temperature (so long as there is still liquid in the tank). He regulator will fit onto all of the standard paintball tanks and will work on tanks with only a pin valve. Stephen