In order to design a better product, sometimes you must let tradition go. The SRAM Force AXST power meter spider is a prime example. Designed specifically for electronic shifting and featuring Quarq's premier DZeroT power measurement technology, the SRAM Force AXST is a huge step forward in power meter design.. AXST enabled for easy monitoring and firmware upgrades . Bluetooth Low Energy and ANT compatible . Power readings are accurate within /-1.5% and aren't affected by climate conditions during a ride . Power balance measures left and right legs separately . Uses a common CR2032 battery that last for 200 riding hours and changes without tools . Power-upgrade compatible with the following RED and Force eTap AXST cranksets: RED 1x, 36T-46T; Force 1x, 36T-46T; Force 2x, 33/46 and 35/48