The SRAM Rival 12 V power sensor measures power on the left side to calculate the total additional watts over the conventional crank.\nIt's easy and affordable to upgrade to a power sensor \nElegant, lightweight integrated design \nThe DUB-PWR unit integrated into the axle measures left leg power and calculates total watts \nProven reliability and accuracy from QUARQ\nLong autonomy to make power talk all season long \nUser-replaceable AAA battery itself\nThe DUB bottom bracket offers simplicity and durability