Held in with silicon.
Flattened the gripper.
Hard to see but its screwed to the inside of the doorskin with the rubber against the glass, hopefully better than a bit of foam thats usually there.
So does it work ? The ones in the outer door frame, yes, a marked difference. the ones inside the door, I will have to let you know as we are all confined to barracks right now.... Stay safe.
Bash