Opus was a relatively nasty brand of tapes which were often sold through Franklins. It was cheap, but not really “cheerful” with problems with tape mechanism and dropout rates. Their supplier was Musicway, which eventually changed their value brand to something else – but I think they even supplied some government agencies at a time.
The cassette itself is relatively unique with a blend of translucenty white plastic and a red hub clip. Other than that, it’s really unremarkable, and the cassette tape itself has a “cheap” smell to it.