Can someone tell what this does?

[PHOENIX]

Thermal vacuum switch.
It regulates vacuum to components based on coolant temperature (engine warm up).
It could be used for a few things.
If the vacuum lines are all hooked up and everything is working fine I wouldn't remove it.
If you do have to keep your EGR you need to keep atleast one of the TVS's with two ports, one in, one out.
My a.i.r. pump vacuum line was not (and is not) routed through a TVS.
My TVS is only used for the egr (i believe there is a line to the canister also).
I used to have a TVS with more ports. One went to the heat riser.
The heat riser is located on the bottom of passenger side exhuast manifold.
It help the engine to warm up faster.