, Engineer Grade Reflective Adhesive Numbers & Letters Label, 25 Markers/Pack, 1.375" x 1.875" Numbers and letters are white on a black background. Made from high-visibility, engineer grade reflective material that conforms to the requirements of FP-79 (Class 1) and LS300C (Class 1). All markers have optical lens elements enclosed within a transparent resin with a smooth outer surface for maximum night visibility. Sheets are retroflected by light in the nighttime.