Dyna-Sys specific (HG-X) 2x10-speed mountain drivetrain compatibility HollowTech-II (HT2): integrated drive-side spindle with outboard, 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) CloseStep trail-tuned ratios optimized for Dyna-Sys 10sp cassettes, providing faster shifts with an improved range of gears Plated aluminum chainrings with DualSpike pin/ramp technology for precise shifting performance, increased durability, and reduced weight Hollow-forged Ultra-Duraluminum crankarm/spider with a 4-arm chainring interface (M980 version uses 64/104mm BCD arms and a blind-hole outer chainring mount for a 46.8mm chainline, while the M985 version utilizes 88mm BCD arms with a single-set nut/bolt chainring mount for a 48.8mm chainline) 690-725g with rings and BB @ 175mm