Shimano MT610 12 Speed Boost Double ChainsetReady for fast and fun MTB rides, this 12 speed MTB crankset gives you powerful acceleration and smooth shifting performance. It features a rock-solid forged alloy crank arm construction, which enables it to withstand all the intensity that's associated with all-day epics in the mountains. Shimano has also kitted out this model with a HollowTech II integrated bottom bracket design for increased stiffness, efficiency and added durability.Features: Crank Arm Material: Forged Alloy Use: MTB Speed: 2x12 speed Number of Chainrings: 2 Chainrings Included: Yes Design: 2-piece Chainline: 51.8mm Chainring BCD: For use with 142/148mm O.L.D. frames 4 Arm or 5 Arm: 4 arm Chainring Size: 36/26T Chainring Mount: Direct mount Chain Compatiblity: For use with 12 speed HG MTB chains only Is BB Included: HollowTech II integrated bottom bracketPart Numbers: 170mm: FCMT610BC66; 175mm: FCMT610BE66Technologies: HollowTech II: HollowTech II integrated bottom bracket design uses a wide bearing placement with a large axle diameter for increased stiffness, efficiency and added durability. Forged Crank Arms: Forged crank arms rigid whilst being incredibly strong and durable.A 2-year warranty is offered with all Shimano products from Chain Reaction Cycles (3 years on Dura-Ace and XTR products).Buy Shimano Components from Chain Reaction Cycles, the World's Largest Online Bike Store.