With this u can mount a camera (with gopro standard mount) in your car using the headrest tubes.
This work with headrest tubes of 12-18 mm of diameter.
If your tubes are less of 18 mm u need some rubber to fit, for examples in my golf tubes are of 14 mm and u used a 2 mm tickness rubber to fit until 18 mm.

To complete u need:

• 9 M5 nuts;
• 6 M5x20 mm screw;
• 2 M5x50 mm screw;
• one tube of 22 mm diameter (alluminum, wood ... but light !)
• some rubber of 1/2/3 mm tickness.

It's easy to mount, no explain needed.

A short demo video:
https://youtu.be/xhD5HsmBOzo