12 1/2" hand brush, blue polypropylene block, filled soft gray polyester. The filaments  are metal detectable and X-ray visible. Should fibers come away from the brush and get into a production line, they will likely be detected by most correctly calibrated metal detection systems. Ask for sample fibers to conduct your own tests. See also #B861RESMDX which has a detectable block as well as detectable filaments, and #DP13MDX for an accompanying detectable dust pan.