Super Small 'Font is, as the name suggests, a tiny soundfont which takes up only 15 kB of disk space. This means it can be used practically anywhere, even on a literal potato of a PC that has a small hard (or perhaps even floppy) drive and possibly still runs Windows 95.
Super Small 'Font is a strictly General MIDI-compatible soundfont. This means no Roland GS-specific features, such as additional percussion sounds or drumsets, are supported.
The samples are from the Microsoft GS Wavetable Synth, except they're greatly compressed. Plus, there are only 6 samples in the soundfont overall.