For those of you who keep your PC ADVISOR CD DISKS in their slim cases.
Did you know that if you fix two cassettes back to back you can store them in a standard CD cassette holder.
Place two cassettes face down on your work surface, both with the hinged end to the left. Take two strips of double sided sticky tape 12 cm long and place them 5mm from top and bottom edges and stopping short of the hinged end by 2cm. Repeat for the other cassette.
Next remove the backing paper from sticky tape on both cassettes and with care place both cassettes back to back, hinged ends to the left and press together.
Having done this you will find they fit nicely into a tower cassette holder.
The reason you need a piece of tape on both cassettes is because the edges of the back of the cassettes is slightly raised and the thickness of the tape will take up this gap.