Disclosed herein is a method to measure and/or adjust combing resistance of fibers by using a brush, wherein the brush comprises: a brush handle; a brush head connecting to the brush handle and comprising a substrate and bristles which are mounted on the substrate, wherein a certain number of the bristles are movable; an activation means which moves the movable bristles from their original positions to different positions; wherein the brush further comprises at least one of the following: a cover for the brush head which is movable between an open position and a closed position, which internal surface can closely face to the tips of the bristles in its closed position, and which has a gap between the substrate and its side ends in its closed position; an indication to match at least one position of the movable bristles to at least one fiber type and/or at least one treatment type; or the combination thereof. By the use of the above brush device, it becomes easier to measure and/or adjust combing resistance of a variety of fiber types.