This is the Teensy Audio board add-on for the Teensy 3.2, 3.5 and 3.6 development boards. This audio board provides you with an easy-to-use tool to add high quality 16 bit, 44.1 kHz sample rate audio to your Teensy project. The Teensy Audio board utilizes the SGTL5000 stereo codec with headphone amp IC to decode and drive audio files and the Cortex-M4 DSP instructions from the Teensy dev board to provide power to a real-time FFT. Each board is also equipped with 3.5mm audio jack for headphones, a micro-SD card slot for storing audio files, and optional spaces for a 25k potentiometer (volume control) and flash memory chip. Headers are not included.
More information is available on the website of Sparkfun and PJRC.