You must use these mounts in conjunction with the Joker concealed bar end mirrors. Even thought the mirrors are excellent the mounts are only average. In the case of mounting on my Night Rod Special 1" handlebars the OD of spreading portion of the mount could be bigger with better tolerances. In order to get the mount to really gain purchase one person has to take large channel locks and hold the distal end of the mount to prevent it from spinning while you tighten down the allen bolt.........and you really have to torque it down for it to seat. Make sure you wrap it with duct tape to help try and prevent marring the mount. I've used other bar end mounting systems on sportbikes that have better tolerances and this problem is eliminated and mounting can be done by one person. Also, important to note not to push throttle side mount in too far or you will bind the throttle linkage.