3M™ Diamond Grade™ Rail Car Markings 983 are microprismatic retroreflective conspicuity markings designed to mark rail cars for enhanced visibility and detection on the rails. Featuring prismatic lens technology, these markings are engineered to provide good visibility at high and wide entrance angles. These markings are available in a variety of colours and configurations designed to meet industry standards. Conspicuity markings with a custom logo are available for regulated vehicles.