XTR Di2 Dyna-Sys 11-speed front derailleur's operation is pioneering, smooth shifting is guaranteed thanks to a microchip communication link with the gear levers. What's more, shifting the rear derailleur automatically trims the front derailleur.11-speed E-tube Di2 compatibleDouble compatible for 38 - 34TRequires SMFD905 MountThe biggest difference you will notice is just how much quicker and effortlessly smoother shifting on the front chainrings is, even under load. The difference in the effort and time to actuate the shift between mechanical and Di2 is truly staggering. The removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretching, but provides effortless gear shifts no matter what the conditions. The front derailleur also trims automatically; the cage moves in response to the position of the rear derailleur on the cassette to ensure no chain rub and a quiet unobtrusive ride, enabling you to concentrate on the trail ahead. Synchro shift compatible meaning a single shifter can control both front and rear shifting which can be fully custom tuned to your riding preferences. Braze-on fit as standard, Modular mounting allows you to choose from a range of mounting options to cater for all frame designs.