Clamp device for attaching a part to a profiled tube

The device (10) has a single-piece clamping piece (15) for partially encompassing a front profile tube (3a), a lateral profile tube (3b) and a rear profile tube (3c). Two hook-shaped extensions (16a, 16b) engage at profile walls (12a, 13a) of the profile tubes. The clamping piece is flexibly deformable between the hook-shaped extensions and attached at the profile tubes by a tightener (30). A holding pin (17) is integrally formed at the clamping piece, where an attachment part e.g. disk (20), is positively held at the profile tubes by the holding pin.