The 105 (FC-5800) Stages Power meter replaces the non-drive crank arm for existing 105 model cranks. Riders looking to add power to their existing crank need only select crank length. The Stages Power meter for 105 fits all styles of 105 crankset including: compact & standard. Standard & black finishes are available.SPECIFICATIONS Accuracy: ± 2% Weight: Only adds 20gr to base crank arm Battery Life: 200+ hours (coin cell: CR2032) Power range (Watts): 0 to 2500 Cadence range (rpm): 20-220 Water resistance rating: IPX7 Frame Compatibility: Most frames see fit guide in our Support section Crank Compatibility: All Shimano Hollowtech II road cranks Device Compatibility: ANT+ Bluetooth Smart Ready Software Compatibiity: Training Peaks Strava Garmin Training Center & others Options Length: 165mm 170mm 172.5mm 175mm Additional Features Tool free battery replacement Active temperature compensation Accelerometer based cadence measurement Wireless firmware upgrades