9" dark blue polypropylene block, filled stiff grey polyester, resin set. The block, filaments and resin are metal detectable and X-ray visible. Should any part of the brush get into a production line, it will likely be detected by most correctly calibrated metal detection systems. Ask for sample fibers to conduct your own tests. The angled material at the sides and front of this rugged, durable bush is superb for cleaning in hard-to-reach corners, while the gripped handle is comfortable to use even in gloved hands.