DNP has announced a product designed for earth-moving machinery in general but above all to be used on hammers and wherever it is necessary to have big ¬ow rates (379 l/min.) at high pressure (30 MPa) in the presence of strong vibrations. DNP says it has therefore created a screw coupling with a safety system capable of preventing the coupling from unscrewing where the locking ring nut system is as simple as it is effective and this has allowed the problem to be easily solved.