I set one of those up for a friends tank and I really didn't like it. First off the regulator has a very cheap feel to it. Secondly the needle valve and bubble counter are designed to be suction cupped to the outside glass and you need to run tubing from the regulator up to the needle valve and then tubing from the needle valve to the bubble counter. It creates a mess of tubing everywhere instead of simply having all of that connected to the regulator itself. Then you have to plug the diffusor in and it's quite large, way to big for a nano. The system as mentioned from others doesn't even come with a solenoid so you have to purchase that separately, pushing the system to about $200. Finally it comes with a very silly co2 indicator that turns, if I remember correctly blue when the co2 is too low and green when it's good, accompanied by a sad or happy face on the indicator.
I honestly don't know what they were thinking with this product.