This is a handlebar bracket for the Nxt headlights.

The Nxt can be mounted in 2 ways. It comes with a newly developed
bracket that fits all standard front forks. This bracket can be replaced
by a single-arm aluminum handlebar bracket. This allows the headlight to
be attached to the handlebars.

This bracket has a diameter of 31.8 mm.

Technical description
Suitable for all Nxt headlights