Octane One 3-PCS Pro Crankset Super strong & very light 3 piece crankset made from high quality seamless cro-mo steel with unique bottom bracket system. This special external BB for 3-pcs cranks is compatible with all MTB frames with Euro BB&8217;s. This solution has similar weight to internal Euro BB&8217;s but is a lot more durable thanks to the Spanish BB sealed bearings in external BB cups. The crank axle is drilled, the cromoly arms are seamless & fully heat treated. The chain line is perfect for MTB! Revised great looking square crank arm shape for 2013. Octane One 3-PCS Pro Crankset Specifications: Arms: 170mm length, heat-treated seamless cro-mo 4130 Axle diameter: 19mm x 10t BB: external cups with Spanish BB sealed bearings by Octane One Compatible with all MTB frames with 68mm Euro BB Weight: w/o BB: ~840g (crank arms axle) Weight with BB: ~995g (total with BB, axle, arms, hardware)