"Caution - Hard Hats Required In This Area" Sign By SmartSign | 10" x 14" Aluminum 4 mil thick vinyl with clear laminate Protective laminate is graffiti-resistant and resists abrasions and chemical attack Most competitive labels are not over laminated Withstands chemical splash Use indoors or outdoors Glossy finish wipes clean Aggressive acrylic adhesive Easy to apply, just peel off liner Patented "Air Release" adhesive from 3M means bubble-free application