Elcaset

Elcaset was an unsuccessful late 1970s physical audio format. It resembled a Compact Cassette, only larger. It used quarter-inch tape running at double the speed of a regular cassette, and provided superior audio quality, but it didn't catch on; around that time technologies were introduced to improve the audio quality of regular cassettes, so the different format didn't offer enough of an improvement to make people want to switch.

Links

 * Article on Elcaset