It is the bracket that converts the module's intended screw-mount chassis into a rail-mount package, saving enclosure back-panel space and simplifying field swaps.
Integration note for the panel builder
The adapter mates the PM 240 FSA's chassis footprint to a DIN rail profile, so the overall depth and gland-plate clearance follow the Power Module's dimensions — not the adapter's. Verify the PM 240 FSA's heat-dissipation path: the adapter does not add forced airflow, so derating for side-by-side mounting on the rail follows the same rules as a screw-mounted unit.