Organ cobs or rollers were used in roller organs, and consisted of a cylinder of wood with pins in them that pressed on the keys in the organ to actuate them. Roller organs were a type of reed organ introduced in the late 1880s by the Autophone company of New York, and were an inexpensive and popular means of entertainment for the US market.
The smaller organ cobs could play 20-note roller organs (such as the cheapest Gem Roller Organ), but larger roller organ models (such as the Grand Roller Organ) were also available that could take larger cobs that could actuate 32 notes. Over 1,200 titles were produced on organ cobs.
Cobs were inserted into the roller organ and pinned in position. As the hand crank is turned, the bellows are operated and the cob is turned. As the cob turns, it shifts to the right, and goes through 3 revolutions, providing about a minute of music.
Roller organs were produced until the late 1920s.