Glass Fiber Pencil-4mm Precision abrader/sander that is used like a marker. Twist handle to push out fiberglass for abrading. Further it is pushed out the wider the area it abrades. Great tool for prepping small areas prior to painting or applying decals. There are replacement glass fibers (PBU1019/2/10) or brass wires (PBU1020/2/10) if using as a mini wire brush!