The Weber DFAV carburetors are originally equipped with a so-called "water choke".
This means that the coil that operates the choke flaps, is activated by coolant from the engine cooling system.
When this system is replaced by either an electric coil or a cable / hand-operated system, you need to connect the coolant supply and discharge hoses which have the rather odd inner diameter of 16 mm.
This joining pipe is made by Weber to facilitate that connection and continue the flow of coolant.
It measures 50 mm in length while if has the aforementioned outer diameter of 16 mm that fits the 16 mm inner diameter hoses and has an inner diameter itself of 12 mm.
There are three machined grooves at each end to offer the hose enough grip.
This is Weber Article Number: 99900.420
* Made by Weber, in Spain *