Busch & Muller Adaptor Bracket 470APB for Head Lights

I recommend this product

I bought one of these to mount a B&M IQ-X light to a GoPro mount under my outfront computer mount. It works, if you cut out the spacer between the two narrower legs, and file down the brackets a little. This is great, as it means I can mount the light up high out of the way under my Garmin. It's also easy to remove (in e.g. the summer) using the GoPro quick release bolt. In summary, a useful adaptor that avoids having to hack into the B&M mount itself.