A device comprising an arm, with a hollow portion, a hub having a stator portion, and an elongated portion disposed into the arm; a rotor with an elongated portion for housing part of a spring. Wherein the spring has a first end disposed in the arm and a second end disposed in the elongated portion of the rotor, and a moveable arm, with a substantially hollow portion operable to receive the elongated portion of the rotor. Certain embodiments may include more than one moveable arm.