4iiii Precision Pro Ultegra R8000 Power MeterDesigned to give every level of rider a professional standard of performance analysis, this excellent onboard power meter measures your outputs to within one percent and uses wireless technology to relay the data straight to your device. Gauging your pedal power and cadence, this Shimano Ultegra R8000-compatible model features 3D power meter technology to read tri-axial crank strain, to produce super accurate riding data. Top-Performance, Precision Power Meter Compatible with a variety of ANT+ and Bluetooth Smart phones, computers and other devices, the Precision Pro syncs with the 4iiii app which lets you monitor the rider compensation scale and other analysis features. Fitting snugly on your crankset, it measures the individual outputs of both legs for a concise and unobtrusive experience and relays the information to your chosen gadget. Coming equipped with a 100+ hour coin cell battery, this top-level training companion helps to keep an eye on your progress mile after mile. Features: Compatibility: Shimano Ultegra R8000 drivetrain Battery Life: 100+ hours on 2032 coin cell battery Connectivity: ANT+, Bluetooth Smart head units, smartphones, and other 4iiii products Technology: 3D power meter technology (patent pending) measures tri-axial strain on your crank Accuracy: +/- 1% Upgrades: Over the air capability Weight: 25g Buy 4iiii Components  from Chain Reaction Cycles, the World's Largest Online Bike Store.