Signs Educate. Signs persuade. Signs sell. COL-MET is the largest manufacturer of steel galvanized nursery sign holders in the industry. COL-MET sign holders are made with prime galvanized steel for indoor or outdoor use. Galvanized sign holders are designed to withstand harsh outdoor conditions and are an economical, durable alternative to plastic signs that fade and crack outdoors. COL-MET also manufactures a variety of special purpose sign holders designed specifically for garden centers. American Made. American Strong. 800-829-8225