I really dislike these things. They get brittle and break in your hand when trying to get them off the glass. They are awful to get back on the glass and drop off as soon as you turn your back. The mess left on the glass is hard work to remove and can treble the time taken to get a good finish. More trouble than they are worth. I have been going to one job for about 6 months. Nice straight forward, clean sweep, no clutter. Today, they had not one, not two but 6 (SIX) stick to the glass bird feeders. I have explained to the customer, that had these been in place when I quoted, I would have refused to take the job. So if they are there on my next visit I will not clean, and she will need another window cleaner. She is probably ringing around for my replacement as I type.