This is a high quality, locally manufactured bracket made from stainless steel and laser cut to fit the connectors.
As the mounting bracket fits between the flange on the 5 pin socket and the metal backshell it may be necessary to loosen the backshell and this requires a degree of care as there is a small grub screw which must be loosened but if undone completely it must be caught as once on the floor it will be hard to find.
Before loosening the backshell make sure that the cable gland is undone or the wire connections inside will be twisted and will break off, the cable needs to be able to turn in the gland easily.
Once the metal shell is loosened enough for the mounting bracket to fit behind the front flange, tighten the shell by turning it up until it is tight and then re-tighten the grub screw. Lastly do up the cable gland firmly but hold the cable so that it does not twist inside.