This Mini Dab Rig with Barrel Perc is simple in design, yet effective in function. As you inhale from the flared mouthpiece, smoke will travel from the 14mm female joint and into the main chamber. Within the main chamber, the smoke percolates in larger bubbles. This is because the smoke is directly injected into the water, which only allows the smoke to diffuse in on large bubble at a time. Once the smoke has been filtered the first time, it travels into the second chamber for a more thorough process.