Bison Model F Series Fine Grinder Hammer Mills. High speed fine grinders best suited for nonabrasive materials such as pulp, wood, grains, minerals, and fibers. 8 sizes: 8×16, 16×16, 24×24, 30×24, 36×24/36, 48×24/36, 60×24/36 inches. Designed for high volume, high speed size reduction.