A while ago I brought the extreme brush and I slated it on this forum saying it was like window cleaning with a toothbrush. However I have recently brought one again and using it with my slx and carbon goosneck is out of this world. No more aching shoulder and its so much quicker and better at cleaning . I seriously think this is the BARCELONA of brushes. Really recommend it 
Dear Alex,
I have put up that recommendation letter that I told you I was going to post. No, don't protest, I insist!
Now if you happen to have the odd SLX pole that is not gainfully employed or a wedge of crisp twenties that you want to send me, well I wouldn't say no!
Bye for now!
Bye!
Bye, bye,
Yours truly,
James

just kidding - I use the extreme brush too! Bye! Bye bye ....

Oh - I don't use the carbon goose neck - just the standard adjustable plastic jobbie.