{HEAD ~ The unit} may also have other pieces such as microphones and speakers in order to allow communication in {TAIL ~ difficult circumstances} to be facilitated 
{ HEAD ~ The unit } may also have other pieces such as microphones and speakers in order to allow communication in { TAIL ~ difficult circumstances } to be facilitated
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH