Yamaha MBM-350 Field-Master Marching Bass Drum Mallets, Large Soft Pile Head Large soft pile head, recommended for use on 26" to 28" drums. Yamaha MBM series Field Master marching bass drum mallets are built to the demanding standards of today's marching bands and drum corps. Built with heavy-duty but lightweight aluminum shafts, each pair has cushioned grips to help prevent slipping.