Countryman E6OW-MI is a Omnidirectional Earset Microphone with Screw On TA4F Connector for use with Beyer and MI Pro Transmitter Models Opus Series TS-100, TS-300, TS-500, TS-800, ACT707TS(TE), ACT801TS(TE), MT103, MT303, MT801 and MT808. Very high quality audio, good rejection of feedback and unwanted sounds. Extremely light and stable on the head. Once shaped to fit your head, the tough springy boom keeps its shape when stored.