A period of {TAIL ~ extended use}, as used in this application, means a period of use of {HEAD ~ more than about one hour}, and generally more than four hours and less than twelve hours 
A period of { TAIL ~ extended use } , as used in this application , means a period of use of { HEAD ~ more than about one hour } , and generally more than four hours and less than twelve hours
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH