It is a adapter which is used for 120mm round extrusion, M401. It is made of plastic and weighs 0.016 kilograms. It is like a decoration. When one end of a aluminum exhibition extrusion is connected to the flank of the other aluminum exhibition extrusion, there will appear two gaps and then the adapter will be used to fill up the gaps. If you want the connection to show a pretty appearance, you can use adapters to finish it. So, if you have the demand for Adapter, LingTong will provide the component separately or on the extrusion and send them for you together.