The invention relates to an arrangement (6) which functions to grip and hold, or release, material (3) with the aid of a number of movable gripping devices (51, 52). A part (57c) which is intended for coaction with the gripping device (51) has a first supportive surface (57g) and a first through-penetrating hole (57h), and the gripping device includes a narrowed part (51a) which, among other things, provides a second supportive surface (51b) which can face towards the first supportive surface (57g). The two supportive surfaces are adapted to abut one another. The gripping device also has a second through-penetrating hole. The centre line (71, 71') of the two holes can be coordinated for common coaction of the holes with a screw (72).