You can find all Garmin accessories and add-ons at Escapa.
Mount the Radar or bike taillight (both sold separately) on a round or aero seatpost using the Quarter-Turn Mount for Garmin Varia.
Includes a mount, 2 adjustment elements, and 4 O-rings.
Compatible devices:
Varia Rear Radar (010-01509-00)
Varia RTL510
Varia RTL515
Varia RVR315