Depending on the application, different bristle stiffnesses are approriate. The Smart Care® TWIN brushes are color coded for easy identification. WHITE - for use on delicate/natural fibers such as wool, staple cut or extra deep pile. GRAY - Synthetic fiber cut pile or commercial wool loop pile carpets. BLUE - Commercial grade carpets, including level loop or low cut pile. GREEN - Commercial synthetic fiber - loop pile only. Not for regular use. YELLOW - Severley matted commercial grade low loop pile carpets. Not for regular use, only severe, "one-time" restoration cleaning. Consult carpet manufacturer and seek approval prior to use.
Note: Price is per brush. TWIN machines require two brushes.