Offered here is a Land Rover central door locking module (or relay). The Land Rover part number is PRC7921. The manufacturer is KIEKERT. The module is also labeled with ‘4050 5300‘.

I have been unable to nail down specific vehicle applicability for this module. I know this module was used in the 1991-93 Range Rover. It is likely that it was used in other model years, and possibly in other models. Before purchasing, please be sure to match the part number above to that of the part being replaced.  This unit frequently fails, and will cause in operational power door locks!