I could not find anywhere to get a motor fan pulley for my Chicago rock polisher. This one looked to be the same so I decided to try it. When it got to me unfortunately the shaft hole was smaller. I decide I had nothing to lose and drilled it out to fit the motor shaft. My polisher is now operational with a metal motor fan pulley instead of a cheap plastic one. It is a bit tricky drilling the shaft hole bigger! The motor fan pulley should be a excellent replacement for the rock polisher it is made for.