A gripper comprising: - a body, the body comprising an attachment to a holding body; - a first gripping jaw extending from the body and comprising a first concave groove having two longitudinal opposite edges (4, 5) along a semicircular cross section of the first gripping jaw: - at least one second gripping jaw having a second concave groove with two longitudinal edges, at least one longitudinal edge of the second concave groove being attached to one edge of the first concave groove either pivotably or detachably; and - at least one closing element (10, 11) for pressing the second gripping jaw towards the first gripping jaw; wherein the body of the gripper is an L-shaped profile and the first gripping jaw extends from the edge of a flange of the body, wherein the first gripping jaw has a semicircular cross section wherein the first longitudinal edge joins to the flange of the body and the second, opposite longitudinal edge is parallel to the edge joining the flange, wherein the second gripping jaw is joined to the second longitudinal edge of the first gripping jaw so that the first edge of the second gripping jaw runs parallel and adjacent to the second edge of the first gripping jaw, wherein the second gripping jaw forms a section of a circle and extends only partially over a gap between the first and second edge of the first gripping jaw such that the distance between the longitudinal edges of the second gripping jaw is smaller than the distance between the longitudinal edges (4, 5) of the first gripping jaw, wherein the closing element comprises locking teeth and a locking loop, wherein the locking loop is attached to the gripper and its attachment to the gripper provides two joints that allow rotation around the longitudinal axis of the gripper, and wherein the locking loop is pivotally attached to the body and the locking teeth are mounted on the second gripping jaw or, alternatively, wherein the locking loop is attached to the second gripping jaw and the teeth are attached to the body or the first gripping jaw. - a body, the body comprising an attachment to a holding body; - a first gripping jaw extending from the body and comprising a first concave groove having two longitudinal opposite edges (4, 5) along a semicircular cross section of the first gripping jaw: - at least one second gripping jaw having a second concave groove with two longitudinal edges, at least one longitudinal edge of the second concave groove being attached to one edge of the first concave groove either pivotably or detachably; and - at least one closing element (10, 11) for pressing the second gripping jaw towards the first gripping jaw; wherein the body of the gripper is an L-shaped profile and the first gripping jaw extends from the edge of a flange of the body, wherein the first gripping jaw has a semicircular cross section wherein the first longitudinal edge joins to the flange of the body and the second, opposite longitudinal edge is parallel to the edge joining the flange, wherein the second gripping jaw is joined to the second longitudinal edge of the first gripping jaw so that the first edge of the second gripping jaw runs parallel and adjacent to the second edge of the first gripping jaw, wherein the second gripping jaw forms a section of a circle and extends only partially over a gap between the first and second edge of the first gripping jaw such that the distance between the longitudinal edges of the second gripping jaw is smaller than the distance between the longitudinal edges (4, 5) of the first gripping jaw, wherein the closing element comprises locking teeth and a locking loop, wherein the locking loop is attached to the gripper and its attachment to the gripper provides two joints that allow rotation around the longitudinal axis of the gripper, and wherein the locking loop is pivotally attached to the body and the locking teeth are mounted on the second gripping jaw or, alternatively, wherein the locking loop is attached to the second gripping jaw and the teeth are attached to the body or the first gripping jaw.