Classic Romanian travel set c1960?

I'd always been curious about these travel sets, so was pleased to pick one up for a good price.  My curiosity was not abated by owning one, however!  I'm still not sure how and why someone invented the interesting mechanism for the board - which, on opening the case, draws the two halves of the board together with a clever little contraption of stiff metal wires, leaving the board "floating" above the case.  Why this is an improvement on the standard Whittington style boards I am not sure!  Please let me know if you know why!

Unsure of dating for this one - I think they have been in production since before WW2, and, as far as I know, up until recently.  My best guess would be 1960s, but could well be later.

The kings, queens and bishops are all identical in shape and size, but are distinguished by different colour painted heads. Kings ~0.6" tall without peg, 0.75" with peg.