The fitting has a height-adjustable support column with a casing element (12) surrounded by supporting pillar ring and surrounded telescopic interlocking axial sliding pillar of support. The casing elements (12) each consist of a ring having curved tape material (14), and has adjacent edges (16) with backward curved seam (20) and a C-shaped profile, which folds to a closing brace (22). The seam (20) has a notch (26) connected to a locking element.
