1. Ground glass stopper.
2. Screw capped adapter, used for thermometers or air bleeds in vacuum distillations.
3. Gas inlet adapter, used to allow delivery of a gas (e.g. a protective layer of nitrogen) to a reaction.
4. Step down adapter, used to connect ground glass joints of different diameters.
5. Step up adapter, used to connect ground glass joints of different diameters.
6. Guard tube, when filled with a drying agent, such as calcium chloride, it can be used to protect reactions from moisture.