A large, four CD, collection of MOD files, which can be played in a number of programs for macs such as PlayerPro, ModPlayer, MacMod Pro or Sound Trecker.

The disks are not HFS, and it looks like while someone has tried to historically put some Macintosh software on the disks in the TOOLs folder... well, they've renamed them to match DOS file names, and obscured the filetypes. Thankfully, despite this, if you drop them on Stuffit Expander 5, it is able to work out what they are and expand them. I'm assuming they are Stuffit Archives.