SRAM RED AXS E1 crank arm assembly delivers championship-grade performance through hollow carbon fiber construction that maximizes rigidity while minimizing rotational mass. Compatible with DUB axle standard and optimized for 12-speed systems, this 172.5mm assembly ships without chainring for complete drivetrain customization. The natural carbon finish showcases SRAM's latest generation engineering, making it the choice for riders demanding uncompromising efficiency and responsiveness on every climb and sprint.