This adapter provides a neat, quick solution for many mounting situations that would otherwise require costly custom fabrication. It consists of two parts: A shank nut & a clamping piece. The stem nut has an M6 internal thread. The clamping piece can be moved & rotated on the stem nut & can accommodate all luminaires with M5 threads (Atto®, micro S, Rhombus S) at any angle. The degrees of freedom of this attachment allow the light to be perfectly aligned in the direction of travel & locked in place with grub screws. The light can thus be mounted, for example, underneath the fittings. To do this, simply replace the nut on the axle of the brake or clutch lever with the stem nut. The clamping piece alone can also be installed together with the handlebar mirror, for example. Suitable for Kellermann Atto® Kellermann micro 1000® Kellermann Rhombus