<p>The screw has a contact part (7) screwed into a passage hole of a clamp. An operating part (8) has an internal thread (14) and a contact surface, and screwed on the contact part. The operating part has an upper part (19) and a lower part (20), where the upper part is designed as a cover with a base area (13). The contact part has defined wall thickness that is guided through the lower part after reaching of the fixed seating of the screw into the clamp and shearing of a part of the contact part and upper part of the operating part for separating an area of the contact part.</p>
