TheSram GX Eagle Boost BB30 12 Speed Chainset.The SRAM GX Eagle™ crankset delivers consistent performance every time out. Featuring SRAM’s X-SYNC™2 tooth profile chainring, the GX crankset is engineered for complete chain control. Each tooth’s thickness is precisely toleranced and controlled to work seamlessly with the chain’s inner and outer links. Only Eagle is a complete system-engineered drivetrain designed, tested and proven to deliver the lightest, highest-performing, most durable system for all riders on any trail. Eagle technology provides an expanded, optimum, gear range making you fast on the flats, giving you control on the climbs and unleashing your speed on the descents. Sram GX Eagle Boost BB30 12 Speed Chainset Features Arm Material: Optimized 7000 series forged aluminum arms Chainring Material: aluminum Weight: 610g - 662g Available Arm Lengths: 165mm, 170mm, 175mm Compatibility: All levels of eagle™ drivetrain systems Colors: Black Bolts: Direct mount (dm) Bottom Bracket: bb30/pf30-68/73mm, gxp 100mm/pf gxp 121mm, gxp/pf gxp 68/73mm Chainrings: 30, 32, 34 Recommended Chain: GX Eagle™ Interface: 24mm, 30mm Other Chainline: 49.0mm, 52.0mm, 66.5mm, 76.5mm