Industry Leading Durability<br>DiamondPlate signs are made of photo-sensitive anodized aluminum plates, great as door signs. The legend or the serial numbers are sealed into the aluminum and cannot be abraded. Plates resist salt spray and chemicals. Unlike other signs, our Please Leave Packages in the Box Diamond Plate Door Signs withstand traffic, constant abuse and abrasion. Signs have a great outdoor life; plates last up to 20 years outside and can resist temperatures up to 1000°F. Signs have a matte finish; so the message is not hidden by glare.<br><br>USA's Oldest Sign Manufacturer<br>Family owned since 1918, we take immense pride in our signage. Being one of the oldest certainly means we know this business in and out. Our South Dakota factory is the oldest manufacturer of outdoor signs in the USA.<br><br>Hassle Free Installation<br>Signs are composed of 32 mil thick aluminum and 5 mil thick 3M 468MP high performance acrylic adhesive backing. Just remove the paper liner and stick the sign to any flat surface. These durable, aluminum signs are simple to install. Once applied to a smooth, flat surface, these signs are virtually impossible to remove. The high bond adhesive permanently fuses the sign to the door and, unlike other door signs, these signs have a thinner profile - which is actually an advantage in this application. Thicker door signs tend to get "picked off".</br>