CeramicSpeed SRAM OSPW System. Features: 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 In the box: complete upper and lower OSPW system, 15ml CeramicSpeed Bearing Oil dropper bottle, and custom installation tool Specs: Model:coated Compatibility:SRAM 12sp Eagle AXS Upper Lower:14/18 tooth Color:orange/bronze