Bolt indicators
Are small pointed tags,which are fixed to the lug nuts of the wheels of large vehicles. The tag rotates with the nut, and if the nut becomes loose, the point of the tag shifts noticeably out of alignment with the other tags. If too many lug nuts are loosened, the wheel can detach from the wheel stud, loose wheel nut indicators allow identification of loose nuts before this can occur,in order to aware the driver.