Abstract: Provided are at least two connecting elements (3, 4) which engage into one another, a first connecting element of which is to be arranged on a workpiece (1) and a second of which is to be arranged on a surface (2) to which the workpiece (1) is to be fastened. At least one of the connecting elements (3, 4) has at least one locking arrangement (8), with the purpose of being able to fixedly clamp said connecting element (3, 4) in its position on the workpiece (1) or on the surface (2). The connecting elements (3, 4) can be arranged in a sleeve (9) which holds said connecting elements and which itself is fixedly held by means of a second locking arrangement (10) in a depression (5, 6) of the workpiece (1) or of the surface (2). For reliable and comfortable assembly of said device, special tools are provided.