The timing belt pulley includes two metric set screws. The Pulley itself is actually made of 3 components- a single aluminum core with the cogs feature and two plated mild steel round belt guides pressed into the aluminum. The core and bore runs true visually with no wobbling but the rails are a little off and there is some minor wobbling (guesstimate .005 runout) which is OK for my purpose. I had to enlarge the bore with a reamer for a larger spindle on a lathe and there is feature on the pulley that allowed the use of a 3 jaw chuck on the lathe- so I was able to hold on to the aluminum portion of the pulley and not hold on the steel belt guides. There are some blemishes and dings but I was able to smooth it out. But what is really good is the extremely low price.