Attach a standard 12mm crossbar to your handlebar clamps. Suits clamps with M8 bolts with 38-40mm separation. Includes longer M8 bolts that will fit most bikes and spacers to let the bars clear the features of the clamp tops.

Wedged hole design gives 3 points of contact to prevent loosening caused by twisting on the bar, and the extra gap near the set screw clears any divots on the bar allows for easy removal and re-installation.

The first picture shows the included parts, the second and third show an example installation.