Think before Stereo. Think Before Hi-Fi Headphones and earphones were out there. For radio operators mostly. The styling made Grado look modern.
The FIRST headphones I recall were little pink plastic round things with tiny twisted off white wires. If you had a good 7 TRANSISTOR radio, it might have a mono mini plug that would take these, so you didn’t need to hold the radio to your ear for private listening.
These also came with the kits for “crystal radios” that were given to grade school boys for science projects circa 1960. With no battery and 100 ft of antenna wire, I could listen to a few clear channel stations.