The Siemens 3UG4983-0C is a sealable cover for the 3UG4583 insulation monitoring relay. It mounts in any position and spans the full 45 mm width of the relay face, with a depth of 107 mm and height of 68 mm — it's sized to enclose the relay's front terminals and DIP switches behind a tamper-evident seal.
The 107 mm depth accounts for the relay body plus the cover's own enclosure — it will project further into the panel than the bare relay, so check clearance to the gland plate or door. The cover seals against the relay face; no additional drilling or DIN-rail hardware is needed beyond what the relay already uses.