Quarq's DZero platform has proven to be one of the most accurate and reliable power meters on the market, with its ability to measure right and left side power within /- 1. 5% accuracy. Recently, Quarq decided to upgrade the power meter chassis by integrating SRAM's DUB technology into the crank arms. The result is a stronger, stiffer, and lighter crankset that more efficiently transfers the effort from your legs into forward momentum on your mountain bike. To take advantage of the complete setup, you need this Dzero DUB XX1 Power Meter Spider, as well as a set of the new DZero DUB XX1 crank arms. Once you have these two components, all you need is a SRAM X-Sync 2 chainring and you're ready to hit the trails. Along with these hardware changes comes a new firmware that employs MagicZero auto-calibration technology. With MagicZero, the system automatically calibrates itself as you ride. You no longer need to backpedal to zero the power meter, and you no longer need to manually calibrate your head unit either. We see this as a welcome relief, as it simplifies the power meter's operation, allowing riders to shift more of their focus to riding and training. Additionally, all power meter related functions have been shifted to the SRAM AXS app. Not only does this give you full control of all AXS components on your bike, but it allows you to set the power meter's zero offset, check battery levels, run diagnostics, and perform firmware updates. The previous software used for this function, Qalvin BLE, has been discontinued. The DZero DUB Power Meter Spider uses a 4-bolt chainring pattern that pairs with SRAM X-Sync 2 chainrings. It's designed to fit 11- and 12-speed SRAM mountain bike drivetrains. And like we mentioned above, it must be paired with the Quarq DZero DUB crank arm assembly. The assembly is sold separately, and comes with a set of carbon cranks arms in multiple length options, as well as the SRAM DUB spindle. You will also need to purchase a DUB bottom bra...