These Central Movements feature hand-built coated bearings, specifically developed for off-road performance, offering extreme durability and featuring a unique design for SRAM DUB 28.99 cranks. The coated bearings use the highest quality CeramicSpeed ceramic balls, which rotate on hardened steel races with a 3-micron thick metal coating, making the races corrosion-resistant, harder, and smoother, increasing service life and reducing friction. Included: 2 CeramicSpeed Bearings 2 Dust Shields Plastic Sheet 1 3mm Spacer 2 1mm Spacers Long Life Grease Adhesive