Pioneer's Shimano Ultegra 6800 Power Meter is a revolutionary power meter that attaches stealthily to the left crankarm. The Ultegra 6800 left crank arm meter truly brings power to the people, and gives every rider power-based (also called watt-based) training performance, allowing you to fine-tune your pedaling to find race-winning form without breaking the bank. With advanced technology accurate to +/- 2%, ANT+ transmitting, active temperature compensation, and a mere 22 grams of weight, the Pioneer power meter is perfect for any cyclist. Additionally, installation is fast, simple, and clean with zero wires, magnets, or zip ties.