An upper housing portion has an integral pressure blade for exerting {HEAD ~ a constant downward force} on {TAIL ~ the advancing protective covering} 
An upper housing portion has an integral pressure blade for exerting { HEAD ~ a constant downward force } on { TAIL ~ the advancing protective covering }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL