This carbon steel forstner bit gives you a clean, flat bottomed hole from any angle. It is excellent for drilling all thicknesses of wood including thin materials and veneers without breakthrough and splintering. Use with hardwood, softwood, plywood, MDF or Melamine. It is guided from the outer rim and will not move off center. This 1 5/8" bit has a hexagon shank size of 5/16". The maximum recommended RPM's for this forstner bit is 450 (hardwoods) and 600 (softwoods).