A dual spool retractor device for seat belts in a motor vehicle including a frame, two spools rotatably mounted to the frame, and a pretensioning system providing pretensioning rotation for both the spools. The spools are pretensioning through the activation of a micro-gas generator. The gas generator can provide gas to a single or a pair of gas cylinders. One or more flexible numbers such as a metal band or cable is used which is coupled to one or both spools via a pulley. Activation of the gas generator forces a piston to move in a manner which exerts tension on the flexible member(s) thereby unwinding the flexible member from the spool pulley and providing pretensioning rotation of the respective belt spool.