Thanks!Definitely a Raymarine GPS (possibly a Raystar 125)
It's not a RS150, totally different shape. Almost certainly a RS125, likely connected to an older C oe E series MFD.I don't think it is a R125.
Take a look at the Raymarine RS150 gps, this feeds directly into a STNG / NMEA2000 network. Rather than pluging into a mfd.
Are there Raymarine Axioms MFDs on board? The internal, built in, gps antenna in Axiom's are known for not being ..... that good inside a cabin.
Hence quite a few Axiom owners fit the R150 gps. I did a few years ago.
If there is an AIS tx/rx on board that is likely to have a separate gps anntena.
Good luck.