white  / grey  / brown  / black brush availability: PRO 35: black – soft / grey – residential / blue – standard / brown – stiff PRO 45: white – standard / brown – stiff ATTENTION: STIFF BROWN BRUSHES – Commercial use ONLY. Require Break in Period before use. To do this: install brushes on machine and run machine for 3 minutes on wet concrete. Failure to break in Brushes could result in breaker tripping or machine encountering difficulty on start up.