The SLX FC-M7120-1 crank features an entirely new construction, using direct mount chainrings, special gear tooth profile for improved chain retention, and a 178mm Q-factor. Superior chain retention Special MTB gear teeth profile improves chain engagement and retention DYNAMIC CHAIN ENGAGEMENT+ Rigid and lightweight design boosts trail-riding enjoyment Hollow forged crank maximizes power transfer while limiting weight HOLLOWTECH II Easier gearing than racing groupsets Q-factor: 178 mm Chainline: 55 mm