BKCJ-0311 - 11-tooth, XD-15 Ceramic Hybrid Bearing, Machined Delrin Derailleur Pulleys for 11-speed SRAM derailleurs. The Jockey Wheels XD15 Ceramic - SRAM 11sp by Enduro Bearings are the ultimate upgrade pulleys for your bike. These precision machined Delrin Derailleur pulleys feature XD-15 Ceramic-Hybrid, radial bearings for enhanced shifting performance and longevity. Made for performance, these pulleys have CN (tight clearance) bearings in the upper pulley to maximize shifting accuracy and C4 (loose clearance) bearings in the lower pulley to allow for chain-line movement.The 500 AF Delrin pulley material used in these jockey wheels is highly durable, rigid, and very smooth. It has a high mechanical tensile strength and rigidity, as well as natural lubricity. It also has high resistance to moisture, caustic chemicals, and UV, making it perfect for bike components. Delrin machines very cleanly and precisely, and its Teflon infused material greatly reduces friction when it interfaces with the bicycle chain. Compared to other pulley materials like aluminium or titanium, 500 AF Delrin with Teflon offers significantly less drag.These jockey wheels also feature Enduro Bearings' XD-15 Ceramic-Hybrid bearings, which are the ultimate high-performance bearing setup. These bearings combine corrosion-proof, cryogenically treated nitrogen steel races with Silicon Nitride Grade 3 ceramic balls. The deep-groove design raceways allow for maximum-sized Grade 3 Silicon Nitride ceramic balls, resulting in increased contact area and improved performance and longevity. These bearings are filled with Kluber NBU52 grease, which only runs better and smoother with time and is highly resistant to being washed out. The Jockey Wheels XD15 Ceramic - SRAM 11sp are specifically designed as an upgrade for most 11-speed SRAM derailleurs. They are proudly precision manufactured in the USA and are available in different configurations and performance levels, starting with Ceramic-Hybrid, Black-Oxide treated Zero Ceramic as a step up, and XD-15 Ceramic-Hybrid as the top of the line option.Compatibility: SRAM 11spBearing Grade: XD15 CeramicEnduro Part Number: BKCJ-0311