Can slipcovers be shipped Media Mail?

[shinobipopcorn]

I didn't think they qualified since they didn't have the actual disc with them:

Media Mail® service has special eligibility requirements for permissible contents. Media Mail rates are limited to the items listed below:

Books (at least 8 pages).
Sound recordings and video recordings, such as CDs and DVDs.
Playscripts and manuscripts for books, periodicals, and music.
Printed music.
Computer-readable media containing prerecorded information and guides or scripts prepared solely for use with such media.
Sixteen millimeter or narrower width films.
Printed objective test materials and their accessories.
Printed educational reference charts.
Loose-leaf pages and their binders consisting of medical information for distribution to doctors, hospitals, medical schools, and medical students.

I've never gotten a domestic package that was opened (international is another matter), but they technically have a right to check media mail packages so ship at your own risk.