The oversized film in the 3M Oversized Indoor Window Insulator Kit, will fit those larger windows and slash your winter heating costs. In fact, it can increase the R - value of a single pane of glass by 90%. Yes, that's ninety percent! And there's more..once you have installed it with the Scotch Tape included, you can shrink it with your hair dryer so it's tight, wrinkle free and clear as glass. Window insulating has never been so easy! Hurry and get the 3M Oversized Indoor Window Insulator Kit so you can meet winter head-on.