This is an anti-vibe mount for 12mm carbon tubes. You can simply insert an o-ring in the spare-outs and mount your motors with these clamps. This way the motor vibration doesn't directly transfer to the carbon tube but there's an insulation between. Whether this actually helps reducing overall vibration still has to be tested. Actually the more mass directly connected to the motors, the better, but there are some multirotor producers who implemented this design already and so I wanted to try it out.... :)