Different from ReSpeaker 2-Mics Pi HAT, this board is developed based on AC108, a highly integrated quad-channel ADC with I2S/TDM output transition for high definition voice capture. Besides, this 4-Mics version provides a super cool LED ring, which contains 12 APA102 programmable LEDs. With that 4 microphones and the LED ring, Raspberry Pi would have ability to do VAD(Voice Activity Detection), estimate DOA(Direction of Arrival) and show the direction via LED ring, just like Amazon Echo or Google Home.
Please note that the package does not contain Raspberry Pi.
Please note that there are no any audio output interfaces on ReSpeaker 4-Mic Array for Raspberry Pi. It is only for voice capture. And you could use the headphone jack on Raspberry Pi for audio output.