"This NorTrac 3-Pt. Post Hole Digger's heavy-duty commercial gearbox with 31 gear ratio develops 729 ft.-lbs. of torque at 180 RPM. Designed for use with tractors up to 40 HP shielded drive shaft with commercial-grade cross journals and quick-disconnect lock ring design. U.S.A. Auger Bit Length in. 6, 9, and 12 sold seperately, Auger Speed RPM 180, Product Type Post hole digger, Shaft Diameter in. 2, Shaft Length in. 3, Torque ft./lbs. 729, Tube Size in. 2 7/8, Gear Ratio 31. 3-pt. Category 1 linkage Category 2 requires bushings Boom and U-frame assemblies of 2 7/8in. dia. structural pipe are assembled in minutes Durable, corrosion-resistant powder-coat finish 6in., 9in. and 12in. augers bits sold separately"