A complete set. ¼ inch through one inch. EXTRA FINE condition and ready to use. Coarse screws for faster cutting in green and softer woods. From the IRWIN website: In 1884, Charles IRWIN owned a pharmacy in Martinsville, Ohio. A local blacksmith who was a customer of Mr. Irwin’s came up with the idea for a solid center auger bit. He sold the rights to the invention to Mr. Irwin and a year later, after patenting the auger bit, Charles Irwin, along with four other business partners, formed the IRWIN AUGER BIT CO.