The back has a thin sheet of rubber material held by turned corners  of the opener.  I have guessed at its age being from the 60s

The similar ones i can find currently , type in and search for "Monopol  Hermetus"  or   "Kvernelands bottle opener " .  So there are the comparisons .................................

So mine has a different caption to the others  so hope someone interested

Also mine has Patina - others have "rust"

weight is approx 40g and height is not big so its a Large letter for postage