Garmin Speed Cadence Sensor Replacement Parts Kit [010-10729-00]
Monitor your pedaling cadence and wheel speed as you ride. You can even use it to train indoors because the sensor attaches to your rear wheel.
WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.
We Also Recommend
Lumitec SeaBlazeX2 Spectrum LED Underwater Light - Full-Color RGBW 
Ancor Adhesive Lined Heat Shrink Tubing (ALT) - 1" x 3" - 3-Pack - Black