XX crank arm with a subtly integrated power meter to record and deliver live, accurate power readings to your head unit Spider design uses a proprietary chainring mount system which allows reduced weight without compromising reliability Dual sided power measurement system calculates total watts it’s subtle, lightweight, and boasts an extra long battery life Compatible with the Flight Attendant system, allowing for total connectivity between all AXS enabled component BB and BB DUB spacers are not included 174mm QFactor