Developed with Quarq and bearing the S-Works badge of innovation and quality, Specialized's SpeedZone ANT Power Spider is set to take your metrics and performance to the next level. This strain gauge power meter is accurate to 0.5% and possesses a self-calibration mode at startup so your results stay accurate. The SpeedZone Power Spider is compatible with all ANT devices, so you can use the GPS unit or computer of your choice.