Elcaset
From Just Solve the File Format Problem
Elcaset was an unsuccessful late 1970s physical audio format. It resembled a normal (Compact) Audio 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.
