These disk labels were offered by Apple in the mid-1980s. At least one photo I located verifies that these stickers were included in the packaging with the original Macintosh (but they may have also been included in other products).
The labels are in their original package and measure 3 x 2.75 inches. The part number printed on the labels is 026-2001A. The back of the labels show disk use safety guidelines.
Originally introduced in 1981 by Sony, Apple used 3.5-inch floppy disks with the original Macintosh. The first 3.5-inch floppy disks were single-sided and held 400kB. In 1986, Apple introduced a double-sided 3.5-inch floppy disk that held 800kB. In 1987, a “high density” (HD) format of this disk was introduced that was advertised as holding 1.44 MB (although they actually held 1.40625 MB).