GRAV® Smoke Upline Water PipeThe GRAV Smoke Upline Water Pipe doesn't filter smoke the way a traditional bong does it filters it progressively. Instead of a single perc at the bottom and a straight tube above it, the Upline features a ladder style chamber where smoke and water rise together through multiple stacked bubbler sections, each one cooling and filtering the draw a little more before it reaches the next. By the time vapor arrives at your lips, it's been through a series