woo hoo! may have pressurized co2!

can any of you tell me what the small holes on the back of this regulator are for? It's a Grundy vcm2000.

co2 regulator 005.jpg
 
So, you would have the regulator attached to the co2 bottle, then the manifold attached to the regulator, (if using one), needle valves attached to the manifold, then out into a reactor or diffuser in the tank. Is this correct?
 
Sorry for the questions, but pressurized gas within my household makes me nervous. :o :hang:
 
AquariaCentral.com