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.