Programmed automatic motion at the touch of a switch makes this derailleur quick, smooth and effortless to shiftThe removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretchingUsing Shimano's shadow plus technology and lowest profile to date, the M8150 will help you squeeze through the narrowest of trails without worryDerailleur contains a saver (fuse) function, where the inner structure is protected from strong impactsAluminium pulley plates for weight saving and durabilitySpecifically designed to work with 10-speed cassette and drivetrain10-speed E-tube Di2 compatibleMax low sprocket: 43TTotal capacity: 32T (Di2 system limited)GS medium cage