The DOT specifies that the 4 digit UN identification number is to be placed on an orange panel. This 2922 corrosive liquid, toxic, NOS panel meets the size criteria and color required by DOT.
Orange 4-Digit Panels
DOT specifies the 4-digit UN identification number to be placed on an orange panel. These panels meet the criteria to be at least 6.3" (160 mm)H x 15.7 (400 mm)W with 3.9" (100 mm)H 4-digit black numbers inside a .6" (15mm) wide black border. Stock signs are in specific UN chemical identification number.