The RCA Victor tape cartridge (also known as the Magazine Loading Cartridge and Sound Tape) was a magnetic tape format designed to offer stereo quarter-inch reel-to-reel tape in a more convenient format for the home market. It was introduced in 1958, following four years of development, at the same time as the stereophonic gramophone record.

Like the later Compact Cassette, the cartridges were reversible and either side could be played; an auto reverse mechanism in players allowed it to run continuously. Playing at 3.75 ips as standard, half the speed of the most common reel-to-reel music recorders which ran at 7.5 ips, the format offered four discrete audio tracks that provided a typical playtime of 30 minutes per side of stereo sound, or double that for monophonic sound; some machines could play and record at 1.875 ips, doubling playing time. Unlike the later audio cassette, but similar to video cassette formats such as VHS, the RCA cartridge incorporated a brake to prevent the tape hubs from moving when the cartridge was not in the player. Small slot windows extended from the tape hubs toward the outside of the cartridge so that the amount of tape visible on each spool could be seen.

Despite its convenience, and a design that would later be echoed in that of the much smaller Compact Cassette, the format was not a success. RCA was slow to produce machines and to license recorded music, and the format disappeared from the market by 1964.