SMA stands for 'Shape Metal Alloy', which is an alloy made from nickel and titanium, and often sold as nitinol or 'Muscle Wire'.
It has the property, that when it is distorted (bent, twisted or stretched), and then heated (to more than 80 deg C), it reverts to it's original manufactured shape. The heating can be done by passing an electric current through it. The SMA we sell is in wire form, and when stretched and heated by electric current under the program of a controller can be used as an actuator, and thus used in the development of robots and in robotic applications.