@stux
I have one of those cases and I never needed to lock it.
I kept all my MIDI disks in there with all the music I was sequencing for a duo I was singing in 1991-1997
We used a Roland SD-35 Sound Canvas MIDI player and put it all through a sound system.
We also used a Digitech IPS-33B Super Harmony Machine to supplement our vocals to get 3 and 4 part harmony.
The case of disks were primarily 720KB. The Roland couldn't read 1.44 MB disks... LOL!