The Grav Labs 10" Nano Helix Straight Tube Bong is one of our favorite products from Grav due it's cyclonic smoking feature. While pulling on the rig hot smoke mixes with cool air in the helix chamber and the Bernoulli Principle is demonstrated. Not all glass is equal glass, this scientific principle creates a smooth and cool smoke which is more tolerable. Additionally you get a lovely visual display of the cyclone created by the air and smoke. This bong features a removable x-cut diffused downstem as a percolation system which works best in approximately 2 inches of water. It alsoÂ includesÂ a removable one hitter to take with you on the go.