KONRAD roofing nails are designed primarily for roofing works such as roofing with tar paper. They are characterized by a large diameter of the head, which is at least three times the diameter of the mandrel, this large diameter of the head is necessary to hold the tar paper on the roof. Roofing nails are also used for upholstery work, and differ from the original upholstery nails in their flat heads. Nails can be black or galvanized.