Power brake filter? Can’t find one

[RecklessWOT]

There's no fluid in your booster, so moisture should not be a problem.

hah, you're right. Reading quickly I thought it was something that went inside the master cyl

 

[Juggernaut]

I always thought the filter was there to protect the engine. The engine is drawing vacuum, wouldn't it pull contaminants from the booster into the engine? Maybe a master cylinder leaking fluid into the booster? What would brake fluid do if sucked into a manifold?