RIVAL AXS D1 12-SPEED REAR DERAILLEUROEM new Battery not included Flattop technology allows for a narrower chain with quieter operation and increased strength and durability Hard Chrome plated inner and outer plates for faster and more precise shifts Requires new Flattop Powerlock On any surface you can imagine, in any drivetrain configuration, the Rival eTap AXS rear derailleur will handle it. Secure chain management and fast, precise shifting make for a smooth and quiet ride, every