This brush does not work on dried on bird poop stubbourn marks and it would definitely not work on bee spots in the summer,also it makes you have to go up and over the top frame otherwise you'll miss the top 3" of the window due to the spay stopping the brush going up and allowing you to rinse on the top section of the window. IMO it's not been tested at all on every type of window just made a nice colour and sold,I can't believe I have just been stung again for another 30 odd sheets for a toilet brush,I might just go back to ionic multipole brushes if I'm honest and just use an average splaying brush for certain work all others out there at the mo are poope.