"Danger - Propane Storage Area, No Smoking" Sign By SmartSign | 10" x 14" Aluminum DURABLE ALUMINUM. Signs are made from heavy-duty, 40 mil thick aluminum. Unlike steel signs, our aluminum signs do not rust. Signs 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. PROMOTE SAFETY.Signs speak volumes about your commitment to everybodys well-being by promoting safety. ROUNDED CORNERS. Signs have rounded corners and burr-free corners for safe handling, longer life and a professional appearance. EASY TO INSTALL. Signs have four 3/16" od corner holes. Mount with screws, nails, tie-wraps or wires. Signs can also be attached with foam or double-sided velcro tape. Sign attachment accessories are not included.