its just for regular cleans, most work is Sill LESS, normally use gardiners supreme soft hybrid, i have a round where there all Sills. saves damaging sills with my normal brush, wiping at angles to get sills wiped over, they get the odd banh with brush head frame.
i would of got a X-LINE SILL brush , i tried to get one at there offer price , but they were not interested in that.
ill try a trusted gardiners Sill brush, i wont know what difference they will do unless i have a go myself. add to my collection