Quarq: DFour DUB power meter spider must be paired with a compatible Quarq DZero DUB crankset and SRAM DUB™ bottom bracket. DFour DUB is designed for Dura-Ace R9100 chainringsEvery innovation in Quarq’s DFour platform represented the 10+ years of Quarq’s advances in power meter technology. This same platform is now combined with SRAM’s innovative DUB technology to bring you the simplest spider-based power meter. Simplified part choices, quality materials and a broader compatibility for bottom brackets and chainrings, brings power on every ride. Features & BenefitsMagicZero™ – automatic calibration as you ride. No need to back pedal or manually calibrate through your headunit.Bluetooth low energy technology and ANT+ wireless data transfer.AxCad – no cadence magnet required.10K Temperature Compensation.Battery – CR2032, 200-hour battery life, change without tools.Power Balance.OmniCal – swap chainrings without affecting accuracy.2-year warranty.IPX7 waterproof rating.Accuracy – within 1.5%, measuring both legs.Free firmware upgrades with the SRAM AXS app.Essential DetailsDesigned for Dura-Ace® R9100 chainrings. Compatible (it will not match aesthetically) with Ultegra® R8000  and 105® R7000 chainrings.Only compatible with Quarq DZero DUB cranks and SRAM DUB bottom bracket.