For easy wire insertion and engagement no matter the appliance system, 3M Unitek offers 3 types of Nitinol Archwires: Classic, Heat-Activated, & Super-Elastic.Developed as an alternative to stainless steel archwires, this "Classic" archwire continues to provide the linear elasticity and bendability of high strength steel and the elastic working range and lighter forces that only a nickel titanium can deliver. It was the first and continues to be the most versatile. Unitek Nitinol Heat-Activated archwire is thermally activated super-elastic archwire. It is the easiest of Nitinol wires to engage and it delivers light continuous forces that effectively move teeth. Unitek Nitinol Super-Elastic is easy to engage and maintains light continuous forces with a range between Nitinol Heat-Activated and Nitinol Classic.