The G3 Stages Power Meter L replaces the non-drive crank arm and is compatible with all Shimano Hollowtech II road drivetrains.Key Features:Handcrafted in Colorado, USA,± 1.5 % accuracy in all conditions,Active temperature compensation firmware,Wirelessly upgradable firmware,Updated accelerometer and addition of gyroscope for improved cadence resolution,Upgraded BLE and ANT+ radios offer a 6X improvement of data transmission strength,Battery Life: 200+ hours (coin cell: CR2032),Power range (Watts): 0 to 2500,Cadence range (rpm): 20-220,Water resistance rating: IPX7.