<VV> what is this part?

[John Lucke]

There's an engine compartment photo with ebay item 190711548864, showing
two little gadgets on the air cleaner cross-over tube between the filter
housing and the carburetors, with air or vacuum lines going to them. I've
taken apart a lot of A.I.R. smog Corvairs, and even have a cross-over tube
with raised flats where these gadgets are, but I've never seen these
before. What are they?