Fsa sl k mtb megaexo chainsetthe sl k double with a four arm design and 10464mm bolt circle is an extremely versatile crankset includes 7075 aluminium chainrings stamped for the inner and cnc machined for the outer theyre designed for 10 speed systems crank arms are hollow carbon fiber with a forged 7075 aluminium spindle between them and alloy pedal thread reinforcement featureshollow carbon fiber arms with ud weaveal7075 100 cnc chainringsal7075 stamped inner chainringcr mo steel chai