The 5Dev R-Spec Trail Enduro Cranks are billet machined from 7050 aluminum, a higher-grade alloy than the more common 6061 spec, with chromoly steel crank bolts and self-extracting hardware throughout. The SRAM 3-bolt Direct Mount interface keeps chainring options open across the aftermarket. What Our Gearhead(R) Experts Are Saying:"The 7050 billet construction is what separates these from a stock crank. The stiffness under load on a long enduro stage is where the material difference shows up."