MONITORING
| Code | Name | Earliest evidence | Confidence | Files |
|---|---|---|---|---|
| M412 | Multi-frequency Oscilator | 1969|2 | high | 103 |
| M413 | Talkback Amplifier | 1969|2 | high | 31 |
| M451 | Talkback Module | 1977|10 | high | 114 |
| M452 | Oscillator Module | 1971|4 | medium | 87 |
| M475 | Monitor Module | 1977|10 | high | 81 |
| M475A | Stereo Monitor Module | 1986|19 | medium | 49 |
| M482B | Monitor Module | 1982|15 | high | 36 |
| M495 | Stereo Monitor Module | 1975|8 | high | 104 |
| M525 | 1985|18 | low (named by) | 30 | |
| M8203 | 2015|48 | medium | 28 |