"Notice - Pool Closed" Sign By SmartSign | 7" x 10" 3M Reflective Aluminum 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 mil thick aluminum. All signs come with pre-punched and pre-cleared holes. Signs last up to 7 years outside. ROUNDED CORNERS. Signs have rounded corners and burr-free corners for safe handling, longer life and a professional appearance. INSTALLATION. With our signs, installation is a breeze. Signs come with mounting holes for easy installation to chain link fences, walls, and doors. GIVE A HEADS UP. Convey your Pool Closed notice with this sign. LAMINATED. Graphics are protected from weather and abuse. Graffiti can be cleaned off. Laminated signs outlast competitive unlaminated or overcoated signs.