CeramicSpeed OSPW Shimano XTR 12-Speed Coated

Proven to be the fastest pulley system, chosen by many of the world's leading cycling teams and professional triathletes
Optimized tooth designs offer 3-5 times longer life than standard OE pulleys
Standard: low drag with hardened steel races and ceramic ball bearings
Coated: metallic layer that covers bearing races making them 75% harder than steel. Even lower friction and highly resistant to corrosion