There have been a few posts recently on here and the DIY board on extending the length of your pole.
This is a simple adapter I use to extend the Zensorflex fishing pole by 12ft.
The adapter is a piece of an old oar, the taper was just about perfect to fit the Zensorflex base section.
I turned the other end down to 30mm, this fits into the Unger no 4 section, so I have added Unger 4 and 5 sections to increase the length by 12 ft.
The bottom shot is the Harris extended by 6ft, along side the extended zensorflex.
I can now do most 3 floor windows with the Harris, including the ones in this shot.