Contact in KY texts me a pic of this little guy. I've not seen one, so had him get it for me. It's about the size of a CD 106 but the pinhole is just over a half inch (guess if it's foreign I outta say 13mm) Any info appreciated. Pinhole pic here: [id=746921379]

Thanks to Rick Soller: it was made by Electro Ceramics in Portugal, assigned U-1175.