Our metal accessible signs are made of durable aluminum which last for years in outdoor conditions. Even our basic 63 mil thick aluminum sign lasts for at least 10 years outside. If you order an aluminum sign with the Diamond Grade Reflective sheeting, the guaranteed minimum durability will extend to 12 years. All the signs are laminated for superior durability and resistance to graffiti, moisture, and chemical splashes. 3M matching ink and film components also contribute to the long life of these signs.