CeramicSpeed Shimano OSPW RS System. Features: Distinctly modern and angular design Design brings balance and refinement to the OSPW System allowing it to blend seamlessly into the contemporary design trends of bikes and groupsets Injection Molded Carbon Fiber reinforced PA cage offers high levels of strength and durability Grade 3 Silicon Nitride ball bearings are 400% smoother, 128% harder and 58% lighter than standard steel balls normally used in the bicycle industry Customizable spring tension settings for optimal setup Available with ALPHA disc pulleys featuring ADR bearing protection or alloy 5-spoke pulleys and standard handbuilt CeramicSpeed bearings ALPHA disc option available with an oversized logo, designated as Team Edition 4-year warranty on 5-Spoke. Lifetime warranty on ALPHA Specs: Model:OSPW RS ALPHA Compatibility:Shimano 9250/8150 Upper Lower:13/19t Color:black