CeramicSpeed's self-characterization as an "efficiency-obsessed" company acts to swoon even the most skeptical road-cyclists among us. In the coated 12 Tooth Aluminum Pulley Wheels you'll find an efficiency-focused performer that reduces friction and pushes durability far beyond what is expected. CeramicSpeed Balls, made from Grade 3 Silicone Nitride, move through strict standards of refinement to ensure smoothness and strength are significantly higher than what is available on the market.Coated bearings not only reduce the watts needed to operate your drivetrain, but also they increase the lifespan by up to 7. 5 times longer than standard ceramic bearings. And a narrow-wide profile for the pulley wheel itself increases shifting accuracy and speed to help you maintain a competitive advantage.