Architectural louvers

Exterior architectural.
Elevator hoistway (above 3 stories)
Bath and dryer vents.

Mailboxes, etc. (Get it?)

Postal service regs require "4B+" mailboxes in new construction/relocation of existing boxes. More space requirements!!!

Here's a link.

Ganged mailbox info for apartment/condo lobbies, including heights, installation details, specs, etc.

And another one.