Busch & Müller Headlight Bracket 475D
Fork crown headlight mount made of durable 4mm stainless steel rod. Designed for (and included with) the Cyo, but works with all Schmidt and Busch and Muller dynamo headlights. This bracket will work with caliper brakes. You'll pass the brake bolt through the lower portion of the bracket and sandwich the bracket between the fork crown and the brake.
Note: if you're using the bracket with a caliper brake you may need to get a longer allen nut for the back of your fork crown, since the brake bolt will be effectively shortened by the depth of the bracket.
The lower part of the bracket (part that attaches to fork crown) measures 18mm, the extension to which the light is mounted is 45mm.
Although not pictured the brackets do include a matching nut and bolt to attach a headlight.