Dowels or other devices fastened in walls or the like by inserting them in holes made therein for that purpose with parts gripping in the hole or behind the reverse side of the wall after inserting from the front with separate {or non-separate} gripping parts moved into their final position in relation to the body of the device without further manual operation {with a locking element, e.g. wedge, key or ball moving along an inclined surface of the dowel body }