This is one of those products that highlights the differences in the US vs. UK market as it pertains to window cleaners.
A light weight nylon brush is all that is needed in UK b/c of the nature of the customer. How long is it between cleanings in the UK? Weeks, maybe a month or so?
In the US its 6 months(if your really lucky) but most often its every year or more.
Nylon bristle brushes do not scrub as well as the hogs bristles.
Window Cleaners in the US gladly pay $80.00US for a hogs bristle brush yet we can not give away a bentley brush.