Quarq's DFOUR DUB Road Power Meter Crankset pairs directly with your Dura-Ace R9100 chainrings to take your training and racing to the next level of precision. Quarq continues to push the accuracy standards of their meters, and the standout feature is the power reading accuracy within /-1. 5%, allowing you to train and race to the numbers and see how you're progressing. Quarq also eases set-up before each ride with their MagicZero feature for an automatic calibration procedure. Once out in the sun or battling months of cold winter, the meter also compensates for changing temperatures for ride-long, consistent readings.The DFour is IPX7 waterproof rated and operates for up to 200 hours on a single CR2032 battery. The meter is paired with Quarq's carbon crank arms in various lengths and requires SRAM's DUB bottom bracket to fit your bike.