Bought 2 units for our entrance bedrooms as we are on a loud main highway. Installed them yesterday and the main difference in noise is awesome. I went with the six.4mm laminated glass and positioned the models on the front on the window sill to give greatest gap. Very joyful https://facial-epilator46665.pointblog.net/getting-my-acoustic-window-upgrades-in-chelsea-to-work-67867887