Cast iron single stage pump which delivers 5.9 CFM at 100 PSI For 1-5 HP. Standard 1/2" V belt. 10" flywheel Head is reversible. Great replacement for Campbell Hausfeld, Emglo, Sanborn and Coleman 1-5 HP units. Mounting holes are 5.75 in" side to side and 5.5"(+/- .5 in) front to back. 860 RPM Min 1300 RPM Max Non unloading heads. Comes w/ flywheel. Same as used on Hitachi, Senco and many other units.