Can anyone help identify this pressure switch

CiSprite1982

I own a 1982 Sprite Compact and have been servicing the hot and cold water system. Its Carver systenm was retro fitted by its previouse owner quite neatly. It has an internal Whale pump and a seperate pressure switch (PS). I am familiar with the white plastic
type whale PS and in fact one came with it as a spare. However, the one fitted is black plastic and, search as I may I cannot identify who manfactured it. I wonder if any of you knowledgeble experts can help? I have taken photos of the system but I do not
see a way of posting them to this forum. Thanks in advance for any help/ advice you can give.