The KTM Superduke 990 is know for having the rear brake reservoir cap come loose and disappear while riding. This can cause the unexpected loss of the rear brake due to brake fluid disappearing as well as the cap. This retainer was designed as a means of locking the brake reservoir cap in place and indexing it to the frame. This retainer is 3D printed and snaps into place and can be removed to service the brake fluid.
I included an "R" version that is exactly the same, but it has the "R" logo on top for extra pzazz if anyone wants it instead of the non logo version.