These are exactly the kind of leads ANY brush will work on and this is a poor example of how that brush works on leaded windows,that lead is so thin it's almost like a plain windows that's being cleaned there. Try it on leaded windows with older thicker lead or flat to the glass diamond leads,also cleaning downstairs you have far more direction and pressure you can apply to the glass,working a couple of feet away you can float it over obstacles but you try doing it 25-30 foot away it ain't happening