The Reels and Cassettes series contains the actual physical tape reels and cassettes. Each reel/cassette is housed in its original reel/cassette case with Westerman's handwritten table of contents on the back. Seeing the wide array of subjects included on each reel illustrates the need for the index card and photocopy system. There are occasional gaps in the reel collection, due to a number of missing reels. Likewise, there is one cassette missing from the cassette collection. The cassettes in the collection are grouped together in volumes, twelve cassettes per volume, with each cassette being numbered one through twelve. The cassette numbering system is as follows: Volume #/Cassette #/Cassette Side.