Abstract: A mechanism accommodated in a hollow bearer of a vehicle for adjusting the height of an upper deflection fitting for the shoulder belt of a belt system, which includes a slide member steplessly displaceable in guidances of the vehicle hollow bearer; one hollow bearer wall is thereby provided with at least one row of teeth or recesses into which the coordinated teeth of a detent member connected with a deflecton fitting and guided in a recess of the slide member, engage against the action of at least one spring force retaining the detent member in its normal position during those occurring tensional belt forces which exceed the tensional forces acting on the belt by the belt user during normal driving operation; a gliding member is thereby arranged in the slide member so as to be displaceable in height, whereby the gliding member cooperates with the detent member and displaces the same up to its engagement at least approximately transversely to its direction of movement during correspondingly occurring tension