Advice 4: Profile width and number of chambers.

Profile width, e.g. 70 mm, 82 mm, 90 mm means how deep does the profile gets into the walls, defines things like ability to install a wider glazing unit or other additions - special inserts that impact the Uw of the window. Windows with a wider profile will have thicker frames, more chambers, will also be much heavier and - in dependence of other available configurations - e.g. warmer.

Number of chambers in the profile is a number of smaller air compartments inside the framem divided with thin walls. Their task is to retain as much heat as possible. More chambers usually mean lower Uw value - a warmer window.