4iiii PRECISION 3+ Ride Ready GRX FC-RX810/RX820 Power Meter Left ArmThe 4iiii PRECISION 3+ Ride Ready is a left arm power meter pre installed on a Shimano GRX crank arm, compatible with both the FC RX810 (11 speed) and FC RX820 (12 speed) gravel drivetrains. It delivers 1% power accuracy and includes Apple Find My support for keeping track of the unit across long days in the dirt. The meter ships in a smaller and lighter form factor than its predecessor, with an automatic terrain selector that adjusts calibration