The TP-8 is a supersensitive microphone for telephone conferencing. Just plug it into the MIC jack of your recorder, and put the earphone side into your ear. When speaking on the telephone, the TP-8 will capture both sides of the conversation for recording on your voice recorder. Frequency is 50 - 20,000 Hz. Ideal for any phone conversations: When speaking on the telephone, the TP-8 will capture both sides of the conversation for recording by your voice recorder. Just plug the TP-8 jack into the MIC jack of your recorder, and put the earphone side into your ear. The TP-8 is recommended for both cellular phones and landline phones including DECT standards. Ear pieces in three different sizes (S/M/L) are included. Box Contains TP-8, Ear pieces in three different sizes (S/M/L).