I have an Extreme Q desktop vaporizer, which is connected to the ash catcher/precooler via a whip. The ash catcher in turn is connected to a recycler bong.
I use the ash catcher as a precooler. The precooler aerates the vapor before it even enters the bong, giving me a head start on smoothness. The recycler does the rest.
I like this step down precooler because it holds a lot of water without overflowing into the bong, which maximizes aeration, which in turn maximizes smoothness.
I have quite an assortment of ash catcher/precoolers but I use this one exclusively now. Completely satisfied.