2 Lithium Metal batteries required. (included)

The speed sensor 2 attaches to the hub of either wheel. You can set up wheel size in our Garmin connect online community or self-calibrate with an edge cycling computer or compatible Garmin device.
Once set up, you’ll get accurate speed and distance at all times — even without a head unit.
Ant+ connectivity and Bluetooth Low energy technology Let you sync to Garmin Connect and other training apps, compatible devices and fitness equipment for better data when you ride indoors and outdoors.