SOLODRIVE 104BCD Single Chainring for 9/10/11-Speed(Narrow-Wide) Super Durable:Made of High quality Anodic oxidation 7075 T6 aluminium alloy,aerospace grade strength Stiff 4mm plate thickness to ensure no flexing Compatible with 9/10/11 speed and origin 3X crankset fixing bolts Narrow Wide tooth design: ensures ultimate chain retention,increases wear life,and reduces friction and noise. Light Weight:44g(32t)/55g(34t)/66g(36t)