DURABLE ALUMINUM: 'Speed Limit 5' signs are made of 63 mil thick rustproof aluminum. They are laminated for protection and use 3M reflective High-Intensity Grade film, assuring more than 10 year durability. EASY INSTALLATION: All signs come with rounded, burr-free corners and 3/8 inch punched and pre-cleared holes. Signs mount to U-channel posts, square or round galvanized posts, wooden posts, and chain-link fences. 3M AUTHORIZED: 3M's "High Intensity" Grade Reflective parking and traffic signs offer up to three times more reflectance than engineer grade reflective signs. They offer great reflectance straight on and even better from an angle. LAMINATED PROTECTION: With lamination, graphics are protected from weather and abuse to preserve a fresh look. Graffiti can be cleaned off too. Clear UV laminate resists chemicals, UV rays, water, and abrasion. PACK CONTENTS: One 18 x 12 inch black and white aluminum sign.