1Alters motors with a different diameter shaft and alters pulleys for a different speed or belt, to provide you with much convenience. 2Works with gas engine crank shafts to enlarge the crank diameter, which will effectively fit pulleys, gear boxes, etc. 3Can reduce the necessity of buying a new motor or pulley, to maintain existing components and requirements of speed or power. 4This iron shaft sleeve adapts a crankshaft from 3 or 4in to 1in diameter, more reliable and practical. 5Simple and easy to use, with high reliability and excellent performance. Features: Alters motors with a different diameter shaft and alters pulleys for a different speed or belt, to provide you with much convenience. Works with gas engine crank shafts to enlarge the crank diameter, which will effectively fit pulleys, gear boxes, etc. Can reduce the necessity of buying a new motor or pulley, to maintain existing components and requirements of speed or power. This iron shaft sleeve adapts a crankshaft from 3 or 4in to 1in diameter, more reliable and practical. Simple and easy to use, with high reliability and excellent performance. Specification: Condition: Brand new Material: Iron Color: Silver Diameter: 3 or 4in to 1 Inch Package List: 2Pcs or Set x Shaft Sleeve