[Eagleback]

I see what your implying. as the brochure shows an aluminum frame. but on the one i saw when they removed the back cap it was open to the interior of the unit. and i didn't see any aluminum in the cap construction. but i didn't tear into it because the tech would say WTH. so i can only tell you my observations that the window screwed into what looked to be a 2x2 frame with the fiberglass laminate on it and what i saw behind the cap was was not particle board but dimensional lumber. Just saying.