Electro-Voice 645TR is a dynamic noise-cancelling microphone element designed to replace the carbon microphone in standard Western Electric telephones. It offers several advantages:

• Improved intelligibility: The frequency response is tailored for maximum intelligibility in noisy environments.
• Noise cancellation: The noise-cancelling design reduces background noise, such as other conversations in the same room.
• Telephone privacy: By attenuating background sounds, the 645TR enhances telephone privacy.
• Easy installation: Installation can be completed in about ten seconds by simply unscrewing the old microphone and screwing in the 645TR.