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