Bought two units for our entrance bedrooms as we have been on a noisy primary street. Mounted them yesterday and the primary difference in noise is amazing. I went to the 6.4mm laminated glass and positioned the units within the entrance with the window sill to provide highest hole. Now https://caidenyfjmr.bloggactif.com/27348526/the-best-side-of-noise-reduction-secondary-glazing