From super fine hairline strokes to big, bold strokes – the Pigma Professional Brush Pen series offers the ultimate versatility. The extra durable, long-lasting and memory-enhanced nibs are made of FB (a tough plastic polyacetal material), MB (a tough nylon material) or BB (a tough porous polyethylene material). Its durable brush nibs respond instantly to changes in pressure or direction, giving a silky smooth, accurate and consistent ink flow.