4iiii Pm Precision, Pro-Shimano 105 R7000-Dual 53-39TFeatures 4iiii makes the lightest power meter on the market. Were committed to helping you get faster, one gram at a time. A dual power meter measures the power from each individual leg to calculate your total power output. Not everyone has the perfect pedal stroke. With + 1% accuracy, 4iiii is the only crank based power meter to use 3 strain gauges to measure all forces in your pedal stroke. Get more data like pedal smoothness and torque