[neilshieh]

That's not a dual stage. It's a dual GUAGE which is commonly confused. Dual gauges just means two gauges, one for the tank pressure (high pressure gauge) and one for the working pressure (low pressure gauge). usual single gauge regulators only have the tank pressure/high pressure gauge.
the milwaukee regulator simon is offering is a good entry level single stage regulator. however with these regulators there have been numerous reports of the solenoid failing and unsteady bubble count as well as the notorious end of tank dump where the contents of the co2 tank are expelled into the tank when the tank is almost empty and the pressure has fallen below 800 psi. dual stage regulators prevent eotd and allow you to use the gas until the cylinder runs empty.
if you're interested in these single stage all in one setups, either get the american made milwaukee regulators (although they're more expensive) or you could try the aquatek regulator which has the same components and cheaper price.
or... you could buy a dual stage setup.