These drill bits are new old stock. They came from an industrial supply company that went out of business. I could not find a maker but they are very high quality. 11/16"x15" with a 5/8 hex shank. Including the hex shank, the overall length is 18".  These bits have a self feeding tip and are perfect for heavy timber, bulk heads, creosoted poles, ties, etc. Drilling with a carbide tip is faster, uses less power, cleaner cuts, and stays sharper longer.