SRAM RED/Force AXS Power Meter Spider - 107 BCD 8-Bolt Crank Interface 1x/2x Black D1. The SRAM AXS Power Meter Spider can be used to upgrade your SRAM AXS crankset to a power meter.AXS enabled for easy monitoring and firmware upgradesPower-upgrade compatible with the following RED and Force eTap AXS cranksets: RED 1x: 36T-46T Force 1x: 36T-46T Force 2x: 33/46 35/48Bluetooth Low Energy and ANT+ compatiblePower readings are accurate within +/-1.5% and aren’t 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 tools.