VIAIR ADA Onboard Air Review
I love this unit. Ive had it for about 2 years now. Mounted in the enginebay.
the best part is the gasps that i get out of people when i open the hood and start airing up the tires.
Its the constant duty unit. I can fill my 37'' KM2s with it before it shuts down due to heat.
If your going to buy one, buy the biggest one you can. Mine has no air tank, or rather, a very small one that is part of the unit, so once its too hot, you have to wait about 30 min for it to cool.
Mine only shuts down when I try to help someone else after filling my tires already.