One lower packing ring set around the valve stem has {TAIL ~ PTFE washers} sandwiched between flexible graphite rings to provide fire safety and {HEAD ~ low friction} 
One lower packing ring set around the valve stem has { TAIL ~ PTFE washers } sandwiched between flexible graphite rings to provide fire safety and { HEAD ~ low friction }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD