The connection device (20) for adjustable connection of a first with a second structural element (12, 13), particularly tubes or rods, for a setting device has an external component (21) with a cylindrical hole and two internal components (22) inserted into the hole so that they can be slid axially and rotatably, each of which said internal components (22) has through openings (24, 25) crossways to the axial direction of the components to hold a structural element (12, 13). By means of loading means (23, 29), designed as a nut/screw connection, the internal component (2) is pushed axially to the external component (21) and thereby grips the inserted structural elements (12, 13). A recess (26) in the internal component (22) effectuates a flexible radial deformation of the internal against the external component (22, 21), said deformation being created through the inserted structural element (12, 13), and an additional bonding of the connection device (20) is thereby achieved, which considerably improves the setting.