FC-R9100-P left hand crank arm. Genuine Shimano replacement partThe choice of the world's best climbers, sprinters, and time trialists, the DURA-ACE R9100 crank drops weigh while maximizing power transfer. The new design, and its iconic look, is adapted for race specific disc brake systems while still offering a wide range of gearing and crank arm length options. The addition of a reliable, accurate, waterproof power meter makes this crank an even more valuable tool to serious cyclists. With a rechargeable Li-ion battery, left/right balance, and Bluetooth LE and ANT+ connectivity, the SHIMANO DURA-ACE Power Meter sets a new standard in cycling data collection.