Open reel audio tape or reel to reel as its also known first appeared in the late 1920’s and between the 1960s and 1980s proved popular with the home audiophile, giving a very high quality audio.
The tape width and number of tracks can vary. With tape widths of 1⁄4, 1⁄2, 1, or 2 inches (6.35, 12.70, 25.40, or 50.80 mm) however the most popular home audio tape was 1⁄4″ (twice the width of the ‘more modern’ 1⁄8″ compact cassette tape). This tape can also be run through the machine at different speeds, slower to increase run time or faster to improve quality, the typical speeds are 3 3⁄4, 7 1⁄2, 15 or 30 inches per second (9.525, 19.05, 38.10 or 76.20 cm/s), again however 3 3⁄4″ in/s and 7 1⁄2″ in/s were by far the most popular speeds used in the domestic environment through the 1960s and 70s.
Tape reels also come in various lengths on 3″, 5″ and 7″ reels. 10″ reels were more commonly found in studio environments.