The holes for attaching the headlight and the holes for attaching the indicators are about ten millimeters in size. My M10 screws fit well. I had to reverse the fork tube brackets to install the headlight into the fork to get the correct spacing between the brackets for mounting the headlight. Otherwise the brackets would be too far apart and not flush with the headlight housing. This left the threads facing outward from the fasteners, so I covered them with acorn nuts. Looks good. The aluminum material seems to be of good quality. Used on 1981 CB750C.