CeramicSpeed OSPW X Pulley Wheel System for Shimano GRX RX820 2x12 - Aluminum Pulley, Carbon Cage, Black EA Cage Assembly

Robust cage crafted from polyamide and carbon fiber for durability and light weight Anodized aluminum 5-spoke 13-tooth upper and 19-tooth lower pulley wheels are light weight and durable Grade 3 Silicon Nitride ball bearings are 400% smoother, 128% harder and 58% lighter than standard steel balls normally used in the bicycle industry 4 customizable spring tension settings for optimal setup Compatible with Shimano GRX RX820 2x 12-speed drivetrain only