The SRAM RED AXSpower meter breaks with traditionand breaks through to new levels of performance. The power meters are designed with Quarqs premier DZeropower measurement technology fully integrated into the crankset. Welcome to the pinnacle of the power meter.These power meter spiders are to upgrade your current non-power AXScrankset.Key Features:AXSenabled for easy monitoring and firmware upgradesBluetooth Low Energy and ANT+ compatiblePower readings are accurate within +/-1.5% and arent affected by climate conditions during a ridePower balance measures left and right legs separatelyUses a common CR2032 battery that last for 200 riding hours and changes without toolsPower-upgrade compatible with the following RED® and Force eTap AXScranksets: RED 1x: 36T-46T, Force 1x: 36T-46T, Force 2x: 33/46, 35/48