Review on Garmin Seat Post Quarter Turn: Get the 010-10644-11 for Enhanced Convenience and Precision! by Tim Burns

I didn't want to entrust this expensive unit to rubber mounts, but reading reviews of this fixed mount, some said it wouldn't fit a 31.5mm or larger seatpost, which was a concern. For anyone considering this mount, my road bike has a 31.8mm seatpost per manufacturer's specs and dimensions (see image). This mount fits perfectly without the included rubber pads and fixes the rear radar light well. I can recommend it as a solid alternative to the rubber band mount that comes with the Varia RTL510.