Garmin USB ANT Stick for Garmin Fitness Devices
Plug the ANT Stick into your computer's USB port and it will automatically receive your activity data when your compatible fitness device is within range. You can transfer your data directly to Garmin Connect (a web-based community of Garmin users who track, explore and share activities) or Garmin Training Center (software to analyze activities and create workouts).
Garmin 010-12843-00 Speed Sensor 2, Bike Sensor to Monitor Speed, Black
Monitor your speed as you ride with this easy-to-install wireless sensor. With no magnets or other exposed parts to line up, this sensor is easy to install, maintain and move between bikes.