4iiii GRX RX810 Precision 3+ Single Leg Power Meter 170-172.5-175mm
Note . if we are out of a specific length of the GRX you can buy the Ultegra arm and use that. Cadence Range: 30 - 170 RPM. Accuracy: +/- 1%. Height: 5.5mm. Power Range: 0 - 4,000 W.