A bentley brush is a standard indoor broom head brought from asda/tesco etc... they are very cheap but will require you to put in the jets, unless you buy them from gardiners etc...
mine did not last very long at all - where as my supalites are doing well 6 months later
i cut down a head just wider than the jets ( approx 8 inches ) for narrow windows or just turn the head round 90 degrees
Darran