BKCJ-0452 - Machined derailleur pulleys made from Delrin, 11 teeth, XD-15 hybrid ceramic bearings for Shimano Dura Ace 12-speed derailleurs - (5 mm bolt hole) - The ultimate upgrade pulley. Guaranteed to last forever against corrosion. Precision machined Delrin derailleur pulleys, featuring XD-15 hybrid ceramic radial bearings for improved shifting performance and enhanced longevity. Designed and crafted for performance, these pulleys have CN bearings (tight clearance) in the upper pulley to maximise shifting accuracy and C4 bearings (loose clearance) in the lower pulley to allow chain line movement. The Delrin 500 AF pulley material offers high mechanical strength and rigidity, natural lubrication, strong resistance to moisture, caustic chemicals, and UV rays, making these pulleys very durable, stiff, and smooth. Delrin also machines very cleanly and precisely. The inherent lubricating qualities of this Teflon-infused material significantly reduce friction when in contact with the bik...