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