Organic chemistry glassware. To create two openings, the Claisen adapter can be connected to a round bottom flask. Equipped with two ground glass joints, simultaneous connection of a condenser and funnel is possible. The adapter is high-quality borosilicate glass. Instructions and illustrations for setting up organic glassware for a variety of procedures, such as reflux and simple vs. fractional distillation, are available in the PDF above under Resources.