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