What is this?

[cattlejack]

Hello, I have a 1972 Winnebago Indian, on the floor at the right side of the driver's seat, there is an orange what looks to be some sort of filter, fram maybe.  What is this and what does it do?
Thanks

[cattlejack]

Make that my other right.  It's on the lefthand side of the driver's seat

[DaveVA78Chieftain]

Air vent for power brake booster
1972-73 Dodge Class A M300 (Late) Motorhome Brakes

[cattlejack]

Well thanks Dave!
Is their anything I need to know about this?  Replace it now and then?

[DaveVA78Chieftain]

Per the Dodge MH Service manual:

[cattlejack]

Ok, is this a filter I can get at any auto store, or do I have to seek it out?

[cattlejack]

Also, what is the lever right in front of it, I think maybe the emergency brake?