Vintage Koss Pro-4A headphones in original box.

Vintage (1960’s - 70’s?) Koss stereo headphones model PRO-4A in original box. They look to be in overall good condition - see pictures - only a few scrapes on top and writing on metal knobs is worn. I tested them and they worked - but not 100%. I had to jiggle the connection to the stereo a few times because they cut in and out. Just putting that out there because they probably won’t work perfectly right out of the box. Super cool army green/bronzish color. Comes with original box but no paperwork.