This allow you to mount your Garmin Varia on your saddle rails, instead of on your saddle bar.
You Need 3 M6 CHC head screw / 3 Nylstop M6 nut to tighten the
...さらに表示 thing.
Garmin mount is reused from what is in the Varia box.
Here is the Fusion 360 file : http://a360.co/2wgi7dT
