Long wearing, general scrub rotary brush. Extra stiff .032" bristles for extra tough scrubbing, available in 12" - 20" diameter showerfeed blocks with 1-3/4" trim. Stiff .028" bristles for general scrubbing. Medium .022 bristles for light general scrubbing, available in 11" - 20" diameter showerfeed blocks with 1-3/4" trim.