This 9" bong/rig is made of thick high quality borosilicate glass, and features an inline disc percolator. Smoke travels through the fixed downstem, to the inline disc percolator, and gets diffused/filtered for cooler hits. This 9" bong/rig is made of thick high quality borosilicate glass, and features an inline disc percolator. Smoke travels through the fixed downstem, to the inline disc percolator, and gets diffused/filtered for cooler hits.