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. FEATURES - Thread Mount design is light, stiff and accurate, and available in 38T-46T - +/- 1.5% accuracy - User replaceable CR2032 battery with 200-hour battery life - Bluetooth low energy technology and ANT+ wireless data transfer - MagicZero automatically checks and recalibrates your power meter as you ride - No cadence magnet required - 10K Temperature Compensation - Waterproof (IPX7 waterproof to 1 meter for 30 minutes) - AXS(TM) enabled for easy monitoring and firmware updates