Abstract: A device for use in conjunction with a standard three-point seat belt harness assembly to provide for restraint of potential rearward motion of a vehicle occupant. The device includes a secondary belt which is fixedly attached to one portion of the harness assembly on one side of the seat and affixedly to the floor attachment post on the opposite side of the harness assembly at the other side of the seat. An adjustable unit is provided on the second belt to tighten across the back of the occupant and for when the seat or the back of the seat is moved or adjusted.