A plug is mounted on {HEAD ~ the plunger} and has {TAIL ~ axial and radial sealing surfaces} 
A plug is mounted on { HEAD ~ the plunger } and has { TAIL ~ axial and radial sealing surfaces }
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL