Stages Cycling Shimano XTR 9000

The 2016 Stages Cycling Shimano XTR 9000 is a power meter. Built right in to the crankarm, it's low-profile, durable, and light. Information is disbursed wirelessly, via ANT+ or Bluetooth; the meter is compatible with multiple software packages, including Strava and Garmin.
A flexible meter, it records RPMs and watt output in a range far beyond most of us, reporting with a tiny error range, less than two percent. Water-resistant and durable, it is designed to survive pretty much anything a cyclist can. The XTR meter is compatible with all current XTR cranksets.
A good power meter.