The present invention is concerned with a locking arrangement having a first wall defining a surface and a second wall defining a surface with the surfaces abutting each other. The first wall is provided with a first bulge defining a first elongate groove facing a first direction and the second wall is provided with a second bulge defining a second elongate groove facing a second direction opposite to the first direction, and the grooves are positioned to define a channel in which a ball bearing is movable there across. The first groove has a substantially same width there across and the second groove has a narrower end and a wider end, the locking arrangement is adapted to, depending on the orientation of the channel, assume a first configuration in which the ball bearing is positioned at one end of the channel or a second configuration in which the ball bearing is positioned at the opposite end of the channel. In one of the two configurations when the channel is oriented to allow the ball bearing to roll to the wider end of the groove, the ball bearing becomes out of a path of relative movement of the walls whereby the walls become movable relative each other and hence unlocking the locking arrangement for the walls.