Abstract: A safety belt retractor including a spring driven belt storage shaft which is locked by either an inertia sensitive, or belt withdrawal sensitive mechanism, or both working together. The width of the retractor is reduced by using a plate-like mass or disc as an inertia sensing mass. The disc is supported, on edge, in a well of a carrier. The carrier can be located in different rotary positions, to adjust the rest position of the mass, by means of meshing gear wheels, one arrangement providing a vernier adjustment. Movement of the mass is sensed by a lever arrangement including a light strip mounted to pivot on, or to rotate with a locking pawl.