Cyclo (76-870x2-2PK) Scrub Brush with Black Stiff Bristles, (Pack of 2) Black Stiff Scrub Brush is recommended for tile and grout, truck bed liners, and some carpets Black is Cyclo's most aggressive brush. This brush provides exceptional scrubbing power on tough surfaces. Used for cleaning tile, stone floors, and pick-up truck bed liners Use genuine cyclo brushes to bring life back into worn carpet pile, to safely remove stains from rugs and headliners, or to clean-up upholstery 5/16-24 inch male thread means this brush useable on other single-head orbital machines such as Porter-Cable 7424XP. Secure metal stud mounting rather than hook and loop methods found on other machine brushes