TThe GRAV® Large Gravitron® is the largest incarnation of GRAV's namesake and flagship product. It's the world's first all glass gravity smoking system, and is just as much of a crowd pleaser today as it was when it was invented in 2004. For the best experience when operating the gravitron, fill the outer chamber with about 10" of water, or until the water level is just below the decal. The bottle should rest inside the water as the included 12mm bowl is lit. Slowly pull the bottle upward and watch it fill with smoke. Finally remove the bowl and inhale through the mouthpiece of the bottle as you push the bottle back down into the water. This creates a pressurized flow of smoke that yields fast and strong hits. The Gravitron's function is impressive to watch, but you'll be even more impressed once you try it for yourself. After a few hits of pressurized smoke zooming straight into your lungs, you'll understand why we love the Gravitron so much.