The XX SL Eagle AXS Transmission Power Meter records and delivers live accurate power readings to your head unit. Utilizing an all-new spider-based design this is SRAM's most accurate high performing power meter. The spider design uses a proprietary thread-on chainring mount system which has allows reduced weight without compromising reliability. A dual sided power measurement system calculates total watts it's subtle lightweight and boasts unbeatable battery life. It is also compatible with the Flight Attendant system allowing for total connectivity between all AXS enabled components. No-compromise high-performance data delivery giving you an edge over the competition.Specifically designed for use with XX SL Eagle T-Type Thread Mount chainrings (Sold separately)MagicZero - automatically checks and recalibrates your power meter as you rideBluetooth low energy technology and ANT+ wireless data transferAxCad -- no cadence magnet requiredPower readings are accurate within +/-1.5% and aren't affected by climate conditions during a rideAXS(TM) enabled for easy monitoring and firmware upgradesCompatible with all Eagle Transmission 8-Bolt cranksWaterproof (IPX7 waterproof to 1 meter for 30 minutes)Uses a common CR2032 battery that last for 200 riding hours and changes without tools