This SAE Recommended Practice applies to retroreflective materials that are used on truck tractors and trailers 2032 mm or more in overall width and with a Gross Vehicle Weight Rating (GVWR) over 4536 kg, and school buses. The retroreflective materials for the truck tractors and trailers are super-high-intensity materials containing microprisms. The retroreflective materials for school buses may contain flexible non-exposed glass bead lens or microprisms.