Black Stallion® Heavy Duty Straps are molded of 100% EPDM rubber to provide the highest possible quality and physical properties. The rubber straps undergo an extensive manufacturing and quality control process to insure each strap delivers excellent performance and value. The straps are manufactured with the graduated TEARDROP design at each end for added strength. The ”S” Hooks are made of silicon kiln-tempered and galvanized steel for extra strength and rust protection. The straps are tested for tensile strength and durometer, for elongation and stretch recovery, and for ozone and cold resistances. Black Stallion® Heavy Duty straps come in 5 popular sizes; 10, 15, 21, 31, and 41 inch to meet a wide variety of applications.