This is a heavy-duty rheostat probably intended for control of filament voltage in older equipment. 5 ohms at 2.24 amps. Unit has an "off" position in the counterclockwise position with the full range just slightly clockwise and the 5 ohm at fully clockwise. Several different brands, Clarostat, Ward Leonard, etc. all rated the same. I have included a picture of 2 different brands for reference. 1/4 inch slotted shaft 2 inches in length. All are new and wrapped in original wrapping.