have since mounted several films at various windows / doors and am totally thrilled. At first I had a little difficulty in mounting but the error then recognized: as soon as the film only very minimal somewhere, eg rubber seal rests, she drops out when the water has evaporated ... ie, 1 mm 'air' to the window frame / to seal etc. can and everything is great (... and not forgetting of course, the wafer-thin support film to remove).