One (1) Weird Wide Electric Disconnect Plug Power Cord Cable Non-polarized Rectangle 1961

These cords were made in the USA or Japan by various manufacturers.  This listing is for one UL listed power cord. The plug that goes into the device is 13/16" wide and 1/2" high. The two male pin contacts coming out of your device should be 3/32" to 1/8" inch in diameter. The male contacts should be five sixteenths of an inch from Center to Center. About 6' long.

There are lots of similar vintage cables! I've tried to photograph some of the similar ones together in the second photo. This listing is circled. This particular cord is very uncommon. If your equipment is Revere or Bell & Howell, you should look for the listing with more rounded corners!

These were standard equipment in the tube era to ensure that when someone opened the case to change a tube, the power to the chassis was automatically cut.  OEM part in 1950s and 1960s vintage USA and Japan-made audio equipment.

These are not polarized, and should not be used in new work unless it is double-insulated. Polarized outlets were not even required by the housing code NEC until 1962!