What stands out about this unit is the bold lettering for model A110-30-11-84 on the cover.
Dehn DPM 255 900 104 Protector 255V 500A 4 KV
A nice touch is how the ABB brand sits on the relay, looking tidy and sturdy at "You will find that with ABB you get a relay that feels familiar to many installers and hobbyists.