Add to wet paint for reflective traffic markings. Excellent for roadways or parking lot use. Sold in 50 pound bags. Potters Premium Highway Safety Marking Spheres are about twice the diameter of standard highway safety marking spheres and provide improved retroreflectivity when specified at the same rounds percentage. Premium Highway Safety Marking Spheres meet or exceed every adopted highway safety marking sphere standard in effect today for North America, including the U.S. Department of Transportation Federal Highway Administration’s FP-03 specifications.