@cyclingeu I am looking for the reverse of this clip:
https://www.stlfinder.com/model/gopro-adapter-for-bontrager-ion-pro-rt-Yqn8cVwI/2187316/
As I have a #bontrager #trek #WaveCell helmet with a triangle shape magnetic thing at the back.
However I want to mount a #picoaprs and / or vhf aerial there.