Dyna-Sys specific (HG-X) 10-speed mountain drivetrain compatibility HollowTech-II (HT2): integrated drive-side spindle with external, wide-stance bottom bracket bearings for optimized rigidity and weight reduction Includes HT2 bottom bracket for 68/73mm shells (BB92 and BB30 adapter bearings available separately) Carbon-composite reinforced steel middle chainring with anodized alloy outer/inner chainrings for increased durability and Hyperdrive pin/ramp design for shifting performance (sizing optimized for Dyna-Sys gear ratios with matching 10sp cassettes) Hollow-forged Duraluminum crankarm/spider with a 4-arm, 64/104mm BCD chainring interface designed for 50mm chainline Both color versions use black chainrings, color refers to crankarm and spider 860g with rings and BB @175mm