Factory Exhause Brake, air or vacuum?

[Jaxom]

Hello All;
I was just wondering what activates/powers the butterfly on the exhaust brake, air or vacuum?
If compressed air, is there an onboard air tank that can be used for other things, such as airing up tires on the truck itself or ATVs?
Thanks in advance.
Jerry.

[mrjordan2u]

I could be wrong, but I was pretty sure it was electronic.