Creating mix tapes is hinted at as a possible use of a pack of UD-60Us. Normal-position tapes (Type I ferric) like these are not the best for high-fidelity audio recordings. I always liked to use Chrome (Type II) or even Metal (Type IV) tapes for my own hi-fi mixes and recordings. Nevertheless, ferric tapes are ideal for 8-bit home computer tape storage.
Mark Tyson opines that Ferric (Type I) cassette tapes are good for 8-bit home computer tape storage, but not for music. For music, he pprefers Chrome (Type II) or Metal (Type IV).