The King Oscillator is a chunky, shiny, steam punk looking safety razor from the 1930s. It takes proprietary blades and those are vary scarce and as far as we know not being made by anyone in modern times. The razor can also accommodate the more readily available safety razor blades, but they will prevent the oscillating action from working as the blade is not slotted to allow movement. We also advice for you to drill/snip/punch the hole in the centre the blade to a slightly bigger diameter if need be, you may see the centre of the blade 'dip' a bit as the guide pin presses down the blade. Some blades work better than others, but if I had such a razor I'd get some original blades and maintain them on a blade sharpening system, the search is on!
A very early patent application was filed in the late 1920's it wasn't until 1932 when King filed the patents for what would eventually become the King Oscillator.
The instruments around today have patents that can be dated to 1936-1938. The specifications of these patents were rolled into the King razor and it's therefore possible to date the razors with the patent no 2089414 to be from 1938 to around 1942.
King was far from the only manufacturer of oscillating razors.
It's fair to say that these razors were a bit of a fad during the 1940's, some battery operated, some electrical, some wound up and some fully mechanical.
The razor weighs 65 grams and stands 96 mm high from end to roller.
a Helpful video here.