In a seat belt retractor, as the rotation of a pawl holder of a locking member in the webbing unwinding direction is stopped by a locking mechanism in emergency, a reel receives a force on a protrusion by impact load applied to the webbing with the inertia of an occupant. These pro-NAD agents may be administered topically, orally, or parenterally to enhance DNA repair and other protective responses to DNA damage. The grippers include a cam block with a cam rotatably mounted in the cam block. The ultrasonic energy may be generated continuously at a constant frequency or at variable frequencies.