The Muntz Stereo-Pak, commonly known as the 4-track cartridge, is a magnetic tape sound recording cartridge technology. The in-car tape player that played the Stereo-Pak cartridges was called the Autostereo, but it was generally marketed under the common Stereo-Pak trade name.

The Muntz Stereo-Pak, commonly known as the 4-track cartridge, is a magnetic tape sound recording cartridge technology. The in-car tape player that played the Stereo-Pak cartridges was called the Autostereo, but it was generally marketed under the common Stereo-Pak trade name.