very true peter but what it the window your cleaning has no reveals,and to turn the brush on and off you have to keep turning the brush though 90 degrees to the frame. Also yes you are right that it is easier to change a brush rather than a trigger, but good triggers are as cheap as £28.00 so for the price of one brush I can have nearly three triggers. Dont get me wrong I actually think the autobrush is a good idea- as good as using triggers and yes I did have a second hand one, just didnt get on with it, I found triggers quicker, easier and saves more water. This is my own opinion using it on my round. If someone elses round is different with a different style window it might be the other way round