Wikipedia
Pocket Disc was a type of flexidisc, made by Americom Corporation and experimented with in the late 1960s by 28 major record labels, (but some major labels such as Columbia Records, RCA Records, Motown Records, and MCA Records chose not to participate) and included popular artists of the era such as The Beatles, Aretha Franklin, The Beach Boys, Steppenwolf and Jimi Hendrix, that were small enough (four inches in diameter) to be carried in one's pocket or shipped in an envelope and not be as fragile as a standard record, but could still be played on the standard manual-only phonograph or record player (at 33 RPM).
Philco manufactured these types of disks under the name "Hip Pocket Records" and sold them to be played on portable record players, which were specially created for the disks. Artists who appeared on these disks included Neil Diamond, The Five Americans, The Doors, Sonny and Cher, Merrilee Rush, and Joan Baez. The disks were sold in vending machines for 50 cents or counter displays at stores for 49 cents and had a capacity of about 3.5 minutes of music. Due to this reason songs like The Beatles' Hey Jude, which was 7 minutes long, could not be played in their entirety Pricing was later dropped to 39 cents. They were first officially released on September 15, 1968 and test marketed in several major cities in the United States, but did not catch on or become a standard music format like their creators and marketers had hoped. They were discontinued in 1969.