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

So I bought this to replace the version that comes with the Varia flashlight which has a strap that holds it to the seatpost. After reading some reviews about size limits I decided to take a chance. I have a Trek Emonda SL6 Pro with a carbon seat post. Well, this Garmin mount doesn't fit my bike's carbon seatpost. The bar appears to be around 35mm in diameter and does not fit in any way. The original mount that came with the Varia fits as it is simply held in place by a flexible strap. Luckily I have a 62cm frame so I was able to use this mount under the seatpost collar as shown in the picture. The bottom of the canopy is still about 4 inches above the tire diameter, so that works for me, but I don't think it will work on smaller frames with the same seatpost. I wish Garmin would post what diameter the mount is rated for so you can make a decision before you buy. However, the bracket is strong and holds tight to the shaft. I think this is safer than the group version. It certainly doesn't move as much as the band's version. He stays where he is.