SRAM RED XPLR AXS Power Meter Spider - For RED XPLR Threaded Mount X-Sync Chainrings 8-Bolt Direct Mount Black E1. When you need the absolute best from your training data the accuracy and reliability of the RED XPLR AXS Power Meter is the way to go. The spider design uses a proprietary thread-on chainring mount system which allows us to reduce weight and increase stiffness without compromising the ability to swap rings. A dual sided power measurement system it’s accurate to +/-1.5% even as weather conditions change and boasts unbeatable battery life.Thread Mount design is light stiff and accurate and fits RED XPLR Thread Mount chainrings 38t-46t (Chainrings sold separately)Dual sided power measurement system it’s accurate to +/-1.5% even as weather conditions change and boasts unbeatable battery life (User replaceable CR2032 battery with 200-hour battery life)Bluetooth low energy technology and ANT+ wireless data transferMagicZero automatically checks and recalibrates your power meter as you rideNo cadence magnet required10K Temperature Compensation and Waterproof (IPX7 waterproof to 1 meter for 30 minutes)AXS™ enabled for easy monitoring and firmware updatesIncludes 8 bolts and thread back up pin for chainrin