Clip Type Connecting Link for D.I.D 520ERT3 Chains. Gold Finish. The D.I.D. ERT3 High Performance Racing Chain has 25% greater anti-shock performance and a 5% higher tensile strength over the previous generation ERT2 chain without increasing the weight of the chain. The D.I.D. ERT3 features an exclusive SDH pin treatment that creates an extremely hard chromium carbide layer on the pin's surface while the inner core is maintained soft to absorb extreme shock load. It also features cold-formed solid bushing technology for high wear resistance and a smooth seamless surface with complete roundness, giving the chain exceptional wear life.