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Housed inside this simple-looking device is the brains of the revolutionary Shimano Dura-Ace Di2 electronic drivetrain. It gives you blink-quick, super-smooth and whisper-quiet shifting. It also constantly monitors your chainline and adjusts itself for zero chain rub. You can go over 1,000 miles before the battery needs charging and it works in all weather and in any temperature. It even self corrects itself should you crash. Genius. The future is here, and we have it! Come check it out!