as dazmond says 25 will reach, defo go with the clx or slx though becasue when poles are vertical they are proper heavy unless the gardiners light range, to make it easier when cleaning windows like this use and underhand overhand grip like the powerlifters do, will give you far more power :-) or..... i didnt say this lean the clx on the roof guttering and use the flexablity at the top to move it up and don to clean the window ;-)