This steel Forstner bit has a 1-5/8" cutting diameter and a 3/8" shank compatible with all standard drill and drill press chucks. Forstner bits are a great choice for cutting clean and accurate flat-bottom holes. Except for the slight notch created by the center spur, the resulting holes are clean and smooth. The middle spur helps center the bit, while the outer rim helps maintain the bits' position when drilling angled or overlapping holes. Steel Forstner bits are sharp and rugged which will perform flawlessly over and over again.