Labeling and Finish mesh perfectly with SRAM drivetrain families. Forged arms increases the strength and reliability paired with our smooth shifting 89-speed chainrings-give you the best combination of looks, performance and price. Our proven Power Spline and classic square BB interfaces are available. Intended to compliment our X. 4 and X. 5 Families. Arm Material: Forged Alloy. Compatibility: 8 & 9 speed chains. Bar Clamp Diameter: 10464mm. Colors: Pitch Black. Bolts: Steel Double Hex Type. Interface: SquarePower Spline.