Materials: Usually steel, stainless steel, or aluminum. Excellent durability and mechanical strength. Fire-resistant and safe for high-heat environments. Because not all environments are the same, junction boxes come in various materials, ratings, and designs. By Material Materials: Usually steel, stainless. Small or large, classic or modern, for standard or special applications – OBO can offer a large range of many different types of junction box for every installation requirement in the different areas of application. The family of the includes our well-known classic brands. Understanding the different electrical junction box types helps electricians, engineers, contractors, and buyers. Junction boxes are typically made of metal or plastic.