Linear actuators are devices that produce straight-line, back and forth, motion. Nitinol wires, springs, and bars can be used to make excellent linear actuators. Springs produce high levels of displacement with relatively low force. The flexibility of wire actuators allows them to be used in applications which go around corners or be used to drive pulleys as part of the actuation system. Rods or bars are excellent for severely high strength applications. While springs can have a wide variety of terminations, wire and rod actuators typically have titanium ring terminals welded to the ends of it for very high strength application.