The HPDA-4 is a flush wall mounted, headphone monitoring station for use with ETS SM1 series microphones. The HPDA-4 is housed in a double gang stainless steel plate for ease of installation on electrical boxes. The HPDA-4 features independent amplifiers and volume controls for up to 4 headphones. The HPDA-4 also features DVR connectivity for live and playback sound monitoring.