COMPATIBLE with Garmin Varia Light/Radar RTL510, RTL515, and RVR315. The Varia adapter can be removed and the seatpost mount can be used as a rear GoPro or Action Camera mount (GoPro adapter not included). The mount fits seatposts with diameters of 27.2mm, 30.9mm and 31.6mm. Plastic spacers are incl...