This is a slot-in design for the IQaudIO Pi-DAC+  ** for use as a Raspberry Pi A+ based Wi-Fi music streamer.  The IQaudIO Pi-DAC+ has a built in headphone amplifier as well as RCA line-outs.  The case can be used in multiple orientations.  The optional bumpers are not necessary, but improve resilience and airflow around the case.  The boards slot into the case from the front and clip in using a lug on the RCA socket.  The lid is secured by the mounting hole on the RCA socket using a small self tapping screw.** http://iqaudio.com/