BKCJ-0361 is an 11-tooth, XD-15 Ceramic Hybrid Bearing jockey wheel designed specifically for Shimano MTB 12-speed bicycles. Manufactured by Enduro Bearings, these jockey wheels are the ultimate upgrade for your bike. They are constructed with machined Delrin Derailleur Pulleys, ensuring enhanced shifting performance and unparalleled longevity.The upper pulley features CN (tight clearance) bearings, maximizing shifting accuracy. On the other hand, the lower pulley utilizes C4 (loose clearance) bearings, allowing for chain-line movement. This unique combination ensures smooth and precise shifting.The pulleys are made from 500 AF Delrin, a material known for its high mechanical tensile strength and rigidity. It is highly durable, resistant to moisture, chemicals, and UV rays. Delrin also has excellent lubricity, reducing friction with the bicycle chain. Compared to aluminium or titanium pulleys, 500 AF Delrin with Teflon significantly reduces drag.What sets these jockey wheels apart is the XD-15 Ceramic-Hybrid bearings. These bearings are corrosion-proof and designed for high performance. They feature cryogenically treated nitrogen steel races and Silicon Nitride Grade 3 ceramic balls. The deep-groove design allows for increased contact area, improving performance and longevity. The XD-15 Ceramic-Hybrid bearings are lubricated with Kluber NBU52 grease, known for its exceptional resistance to being washed out.These jockey wheels are an exclusive offering from Enduro Bearings. They are engineered to be an upgrade for most 11-speed Campagnolo derailleurs. With their precision manufacturing in the USA, Enduro Derailleur Pulleys are available in various configurations, including Ceramic-Hybrid, Black-Oxide treated Zero Ceramic, and the top-of-the-line XD-15 Ceramic-Hybrid.Compatibility: Shimano MTB 12spBearing Grade: XD15 CeramicEnduro Part Number: BKCJ-0352