Excellent! I have a custom Grab Labs Stax bong with two consecutive ash catchers, a Coil Showerhead base, a Glycerine Coil perc, topped with the Helix Mouthpiece. I was already happy with the the cooling effects (the smoke hits my lips at about 55 degrees F) of my original setup. However, the addition of the Helix Mouthpiece not only lowers the draw pressure, allowing the herb to smolder rather than incinerate, and acts a repository for cold smoke (cool air doesn’t rise). I am now taking bong hits with zero lung burn and almost zero urge to cough from even the most dense smoke. $99 was a little pricey, but I can’t argue with the benefits.