Tiffin manufactures the windows for their coaches and have, to the best of my knowledge, since at least the 2007 calendar year. My coach (a 2008 model year Allegro Bay 35TSB, actually manufactured around May 2007), had all windows of Tiffin manufacture except the bedroom emergency escape window which was manufactured by [I]Hehr[./I]
Tiffin's warranty on their windows is 3 year parts & labor, 4th year parts only. I'm not sure if the warranty extends to a 5th year. With a little luck, I won't have to find out ...

They also told me the warranty on the
Hehr window was 3 years.
During the 1st three years, 4 Tiffin manufactured windows and the one
Hehr window fogged. Three of the Tiffin windows fogged prior to an appointment I had at Tiffin in Red Bay, AL, & all 3 were replaced. The
Hehr window and the 4th Tiffin window fogged after that appointment and Tiffin sent me replacements. However, the
Hehr replacement window was made by Tiffin. I could have taken the windows to a dealer for replacement, but having watched the 1st 3 replaced, I opted to do the work myself.
A 5th window fogged during the 4th year and Tiffin sent me a replacement for that one under the 4th year parts only warranty.
Long story short, while it wasn't fun to have these windows fog, I have to applaud Tiffin for their warranty policy and standing behind their products!