What is this part?

[Perfectreign]

While working on my fuel injectors last week, I saw this globe-shaped thingy in the engine bay. I cannot seem to find a description of it in the interwebs.
Here's a picture from another thread here on TDI club from user Seatman. Any idea what it is?

It is just in front and to the right of the block with a blue hose sticking out.

 

[gatz]

Vacuum reservoir. Its just a hollow ball hooked up to the vacuum system to serve as a bit of a reserve / buffer.

 

[Perfectreign]

thank you! Amazing that I couldn't find that out. I appreciate the response.

 

[AnotherPerson]

Back in the day they were actually large food cans. Maybe that's what you knew them to look like?

Original and than replacement pictures lol

Sent from my iPhone using Tapatalk

 

[Perfectreign]

that is an awesome ghetto mod!

 

[Rembrant]

The later ones have a tinfoil hat, I have one on my Golf.

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/vacuum-tank/038129807/

 

[turbovan+tdi]

Back in the day they were actually large food cans. Maybe that's what you knew them to look like?

Or coffee cans,

 

[Perfectreign]

lol - that would be great to actually see