The SRAM Apex DUB Power Meter Upgrade is a left side crankarm that instantly transforms your standard crankset into an accurate power meter. All of the technology is tucked away inside the DUB spindle to measure left side pedaling power and calculate watts. With reliable Quarq technology, you can count on the best readings to guide you on your ride. 400+ hours of battery life mean that you only ever have to worry about riding. It can be used in any weather thanks to an IPX7 water rating. The SRAM Apex DUB Power Meter Upgrade is an excellent way to improve every ride.