Need to replace the roof vents... Brand?

I am wanting to replace the vents on my TM. I have looked at a couple of different brands, but not finding one that fits. Of course, the 14 inch square hole isn't the problem, it's the thickness of the roof.

Now that I've ordered two different types that said they would fit and they didn't.... anyone able to tell me exactly what brand these vents are so I can order them (should have asked here first...). Or do I need to order these from the factory?