Squire Cogswell model 3NL compressor. These were high quality oil-free air compressors with oil in the crankcase and a vented distance piece to keep the oil away from the piston. Out of production for a couple of years, a lot of them were used for medical air systems, and many of them are still running.
This unit had only about 3000 total hours when removed from service in a hospital. It is in top-notch condition.
Complete with baseplate, 7.5 HP 3 phase motor, drive sheaves, belts, and belt guard.