5-arm, 130mm BCD, Aluminum 7075 T6, black SB-packed, suitable for Stronglight, Shimano, SRAM Road cranksets. The revolutionary chainrings from O.Symetric. Non-circular shape for a 10% increase in power, better acceleration. 10% reduction in muscle lactic acid production, no other chain length necessary. Number of teeth 42 Type article Fastening 5-hole Group affiliation Shimano Main color black Bolt circle 130 mm