It depends on your needs. There are a few different material options for our signs, and they can have various levels of durability. You can see the specifics for each material by clicking on the “i” icon next to the material name on a product page. In order to be MUTCD-compliant, all street and road signs must be made with a retroreflective material such as Engineering Grade Reflective Aluminum, High Intensity Prismatic Reflective Aluminum, or Diamond Grade Reflective Aluminum.