Acquired two models for our front bedrooms as we are on a noisy most important road. Installed them yesterday and the difference in noise is amazing. I went with the six.4mm laminated glass and positioned the units around the entrance on the window sill to provide highest hole. This Web-site https://juliusksvzd.blogsvila.com/26960613/not-known-factual-statements-about-noise-reduction-windows-in-chelsea