SRAM RED XPLR AXS Power Meter Spider - For RED XPLR Threaded Mount X-Sync Chainrings, 8-Bolt Direct Mount, Black, E1When 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