What’s the difference between an O-Card (Cassingle sleeve) and a Norelco Box Sleeve?

A Cassingle is a cassette tape packaged only in a paper sleeve called an O-Card, which is printed flat then glued on one side to create a box that’s open on both ends. The sleeve neatly slips around the cassette shell to protect it and provides space for art, titles and credits.

O-Cards (Cassingle sleeves) are often confused with Norelco box sleeves, which are constructed similarly, but at a larger size that slips around a plastic Norelco box containing a cassette. J-cards, U-cards and/or download cards may also be packed inside the Norelco box along with the cassette tape.