This nylon floor scrubbing brush is much softer than the standard poly brush that is made for the 18" CleanHound Scrubber auto scrubber. This brush is strongly recommended for rubberized floors. These rubber causes high amp draw on the brush motors when using normal brushes which could lead to blown brush motors. The thinner 0.35mm nylon bristles on this brush reduce friction, reducing the amount of work your motors have to exert while scrubbing.