The Sony ECM-166BC is a unidirectional lavalier, that features a 1.2m cable and a SMC9-4P connector for use with the WRT-822A and WRT-860A beltpack transmitters.
| Transducer | Electret Condenser |
| Polar Pattern | Unidirectional |
| Frequency Response | Approximately 40 Hz - 15 kHz |
| Dynamic Range (Typical) | > 80 dB |
| Signal-to-Noise Ratio | > 52 dB @ 1kHz |
| Maximum Input Sound Level | Approximately 111 dB @ 1kHz, (1% THD) |
| Power Requirements | Mike Gets its Power From The Wireless Transmitter |
| Output Impedance | Approximately 200 Ohms |
| Output Connectors | SMC9-4P Connector for use with the WRT-822A and WRT-860A Beltpack Transmitters |
| Case | Protective Carrying Case |
| Pad | None |
| Low Frequency Roll-Off | None |
| Applications | Wireless Videography |
| Dimensions | .59 x .34" (14.5 x 8.5mm) LxW |
| Weight | 0.07 oz. (2.0 g) |