XX SL crank arm with an 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 unbeatable battery life Compatible with the Flight Attendant system, allowing for total connectivity between all AXS enabled components Choose 168mm or 174mm Qfactor (check frame manufacturer for specs) BB and BB DUB spacers are not included