Window Cleaners

[Wingedharpy]

Has anyone ever used those window cleaning products that are sold which claim to help keep your windows cleaner for longer?
If so, are they any use or not?
I'm looking for something which would enable me to clean my windows annualy if possible! (well, I can but hope).

I've bought the battery operated Karcher one. Haven't used it yet tho

Wow. I didn't know anything about battery operated ones. I was thinking more of the stuff in a bottle that you get from Lakeland and such places.
Any views?

Will report back when i use it