... Balun + Filter + X’Tal. + PCB antennaWireless communications module conforming to Bluetooth version 2.1 + EDR, class I. UART, USB, PCM, ... no external headphone amplifier is needTwo microphone input to improve echo cancellation and background noise reductionI2S and ... sink to less than 80msApplications, stereo/mono headset, automotive hands free, wireless speaker, and wireless Microphone bluetooth pcb