Soft Black Disk Scrub Brushes for SUNMAX RT120 Dual Brushes Floor Scrubber  Machine (Pack of 2) Soft Black Brushes are: Used for gentle cleaning and polishing of delicate floor surfaces. Designed to provide a milder cleaning action that won’t scratch or damage sensitive floors. For tasks that require a careful approach while still effectively removing dirt and grime. Suitable for surfaces like hardwood floors, marble, tile, and other delicate materials that more aggressive brushes could easily scratch.