Get double the rotation with the 5.5" GRAV Circuit Rig. The angle of the intake hole causes water and vapor to spin rapidly and form a powerful centrifugal force. This cools the vapor and makes each hit smoother, and the twin stacked chambers multiply this effect. There's no need to worry about splash-back with the 5.5" Circuit Rig, because the sharp bend in the mouthpiece keeps all water inside the rig. This piece includes a 14mm female-jointed dome-less nail made of heat tolerant quartz, so all you have to do is add about 0.5" of water and then you can get right down to the fun stuff