C-45 (22:26 minutes per side) HiFi audio tape in brand new cassette shells.

These are newly manufactured cassettes with polyoxymethylene (Delrin) rollers and hubs and graphite liners for smooth silent running. 

Polyoxymethylene is commonly known as Delrin or POM. Delrin has a low coefficient of friction, making it ideal for applications where sliding or rubbing surfaces are involved, such as cassette hubs and rollers.