I was looking to put my Varia on a second bike without having to move the mount as well

The elastic band one requires you to hold the mount when twisting on your Garmin device.

Perfect mount (round seat post) for the Garmin Varia Radar

I didn’t want to trust this expensive piece of equipment to rubber band mounts, but when I read reviews of this hard mount, some claimed it did not fit a 31.5mm or larger seat post, which was a concern

This mount works great for my bike

This mount works great for my bike

This mount fit perfectly, without the included rubber shims, and it secures the rear radar light well

Solid mount though.

Garmin in their quest for more of your money provide a very sketchy mount for a device that costs a substantial sum of money and which, if it were to become detached would leave you without any taillight but probably out said sum of money (in my case over $150)