the pocket or the like the retaining projection 29 is effective in particular if the protective cap 3 is fastened to a comparatively flat object for example a piece of paper or cardboard as is apparent in particular from fig2 and 3 each blocking element 28 is in the form of a two limbed spring clip each blocking element 28 is fixed to the inner surface 27 of the fastening clip 23 by a retaining limb 30 the retaining limb 30 extending from the inner surface 27 obliquely in the direction of the opening 16 and therefore also in the direction of the fixed end 24 and tapering increasingly with increasing distance from the inner surface 27 a knee 31 at which the retaining limb 30 merges into a free limb 32 is formed at that end of the retaining limb 30 that faces away from the inner surface 27 the free limb 32 is angled away from the retaining limb 30 preferably by an angle of between 60 u00b0 and 100 u00b0 so that its free end 33 is in turn orientated obliquely in the direction of the inner surface 27 as emerges in particular from fig2 the free limb 32 is configured to perform a comparatively wide supporting surface 34 that provides particularly good resistance to the cloth of a pocket or some other soft object to which the protective cap 3 is fastened without in the process damaging or even tearing the cloth or object as can be seen in particular in an overall view of fig1 b and 2 three projection like stops 39 are provided in the interior 14 of the protective cap 3.