For decades I've bought my fair share of "OEM Quality" parts. WHEN PARTS ARE MANUFACTURED, STOCK QUALITY IS SO IMPORTANT THAT BUYING A TRUE OEM IS THE WAY TO USE. The unit was a few bucks more expensive than most supply markets, but the difference in price isn't worth estimating, it's the long-term DURABILITY of the unit itself, maintaining consistent belt tension and bearing noise. Change the pulley and the V-ribbed belt at the same time and you will be surprised at how QUIET the engine becomes. THIS IS ONE OF THE WAYS THAT PURCHASING A GENUINE OEM PART WILL VALUE YOUR LONG-TERM PEACE OF MIND AND PREDICTABLE PERFORMANCE.