"Fire Sprinkler Riser Inside" Tag By SmartSign | 2" x 6" 3M Engineer Grade Reflective 3M AUTHORIZED. Authorized signs are certified to the 3M Matched Component System. This assures that signs are durable outside. DURABLE ALUMINUM. Signs use 3M reflective Engineer Grade film mounted to 40 mils thick aluminum and last up to 7 years outside. LAMINATED. Graphics are protected from weather and abuse. Graffiti can be cleaned off. Laminated signs outlast competitive unlaminated or overcoated signs. INSTALLATION. All signs come with four 1/8" od punched and pre-cleared holes. Signs mount to S-hooks or jack chains.