{TAIL ~ mounting fixtures} configured to mount said {HEAD ~ device} on a head of said first user, 
{ TAIL ~ mounting fixtures } configured to mount said { HEAD ~ device } on a head of said first user ,
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH