This System 100M is fully functional and in great condition.
This100M features the standard array of modules known as the "D-Set". This includes the 112 Dual VCO, 121 Dual VCF, 130 Dual VCA, 140 Dual ENV + LFO, and 150 Ring Mod/Noise/S&H/LFO.
The System 100M is vintage roland modular synthesizer format with an array of modules available, typically found in system sets of different configurations. The 121 VCF is a dual 24 dB Lowpass OTA filter that has Roland's warm, bubbley filter characteristics.
The System 100M is an excellent way to get a vintage sound with modular control. Price-wise, you would spend nearly as much buying the equivalent in Eurorack format. Speaking of Eurorack, the 100M is an excellent complement--two full vintage voices sound great when combined with the advanced functionality of modules from the likes of 4MS, Intellijel, and Make Noise (to name a few).