21. The expert from Poland informed GRSG about the purpose of ECE/TRANS/WP.29/GRSG/2016/4, proposing to insert into UN Regulation No. 55 an amendment imposing a new general constraint for granting component type-approval for mechanical coupling devices dedicated to category M1 vehicles only if they were designed to tow trailers. He announced the submission of the document to GRRF for consideration at its next session in September. GRSG endorsed that position and agreed to remove the agenda item.