Bought two units for our entrance bedrooms as we're on a noisy most important street. Mounted them yesterday and the difference in noise is astounding. I went with the 6.4mm laminated glass and positioned the units around the entrance in the window sill to provide most hole. One more reason https://caidenvbgjm.ourcodeblog.com/26919139/the-greatest-guide-to-slimline-secondary-glazing