Abstract: A built-in sink made of a plastic composite material is secured in an opening formed in cover plate having a surface for placing a downwardly facing supporting surface of the built-in sink thereon. A securing element having a main body is attached to the built-in sink. A clamping member is held on the main body for displacement in the direction transverse to the cover plate and adapted to be tightened against and supported on the cover plate. A clamping screw is held in a thread of the main body for pressing the clamping member against the cover plate, the thread of the main body being oriented transversely to the cover plate. In order to minimize the manufacturing costs, a slot extending at least approximately parallel to the cover plate is provided in an underside area of the built-in sink located opposite the circumferential surface of the cut-out opening in the cover plate.

Abstract: A built-in sink unit with at least one basin, which has first surface areas, such as the bottom of the basin, subject to severe wear during use as well as second surface areas, such as the side walls of the basin, subject to less severe wear during use and in which the first surface areas are provided with a three-dimensional surface structure and the second surface areas are smooth. To ensure that any surface damage in the region of the surface areas subject to severe wear during use does not immediately catch the eye, the built-in sink unit gives the optical impression, when new, of really being a new article and the sink unit can, finally, be cleaned effectively with abrasive means without any disadvantageous optical effects thereby resulting, the surface structure of the first areas is formed by microgrooves at least approximately straight and extending parallel to one another, the surface roughness measured transversely to the longitudinal direction of the microgrooves being greater than 0.1 .mu.