(57) @ A coupling device, for a freight container provided at each of its four corners with a mounting plate (40) having an aperture (42) therein. The device comprises a body (6), comprising a flat base plate (10) and a mounting ring (12) with an aperture (14), and an integral head (8) having a portion (20) spaced from the body (6) by a stem portion (18). The head portion (20) has a cross-sectional dimension which enables it to be inserted through the aperture (42) in the mounting plate (40) in one orientation but not in an orientation significantly displaced therefrom. Mounted on the body (6) is a locking member (28, 30) movable between a retracted position and an advanced position. In its advanced position, the locking member (30) lies alongside the stem portion (18), being partially located within a groove (22), and rotation of the device into a position in which the head portion (20) is in alignment with the aperture (42), and thus may retract from the mounting plate (40), is prevented.