The Lab Society biomass flask (5L) is specifically designed for steam distillation to optimize the extraction of essential oils/terpenes. Stacks in tandem with a 2L dual neck round bottom flask to keep the biomass and water/steam in separate areas. This allows the biomass flask to stay dry. Having separate chambers for the plant material and steam/water will also allow for less chance to burn your plant material during distillation. This American-made flask is lab-grade borosilicate glass, with a 45/55 top jointand a 24/40 bottom joint.