What is "spools"

Usage examples of "spools".

He had taken the spools containing the recording tape out of his pocket and was joggling them up and down on the palm of his hand.

Recent issues of the newspaper were stored in large file drawers according to their dates of publication, while older issues were on spools of microfilm.

Returning to the spools of microfilm and also to the hardcopy issues of the daily Register, we continued our research.