This isn't the gravity bong you remember. Made out of durable scientific glass, the Grav Labs Gravitron brings some class to the classic design. If you've never used a gravity bong before, the process is as simple as it is effective. With the bottle inside, fill the cylinder with water until it is roughly 2 inches from the top. Slowly lift the glass bottle as you light the bowl and watch the bottle fill with smoke. Once the bottle is full remove the bowl carefully, any downward motion will push your smoke out of the chamber. Place your mouth on the mouthpiece and slowly push down as you inhale. Start off with a smaller amounts of herb, the hits from this piece can surprise you.