Uses 2 hex wrenches to tighten or loosen bolt/nut Includes (5) 5mm-broach bolts, (5) 6mm-broach nuts, and (5) inner bolts: available in either steel or aluminum (8.5mm) For 4-arm and 5-arm cranks, Road and Mountain Triple Alloy material: alloy-outer/steel-inner Double/Single DH ring style: Use without washers for two chainrings, with washers for one DH ring XX-double version uses Torx-T25 broaches for a 4-arm crank XX/X.0/X.9/X.7 versions do not use nuts due to direct-thread design into outer chainring and inner spider interface