What is the material The body is aluminum.The lock mechanishs are made with other metals. The wire is galvanized steel wire rope, we can make the seals with stainless steel wire rope personalized for the different customers. It is non-preformed cable (npc). How much is the tensile strength We tested the seals in the general weather, the tensile strength is more than 170kgs (375lbs) . Please check the pictures.