The pump allows for forcing the air/co2 through a small orifice to form smaller bubbles. The rig also conserves co2 in the off position. It increases pressure with in the tubing to allow for an increase in depth in your aquarium. I got the air stone sitting at an 18 inch depth with in the tank. More contact time with the water the more the co2 will have to dissolve. CO2 dissolves 200 times more readily than O2.
It really was simple to put together, about 20 minutes.
The air stone is not a stone but a 2mm ID piece of styrene tubing. One end was melted together and then holes were pierced using a 22 gauge needle.