{HEAD ~ A piston pump} 17 wherein {TAIL ~ said wear pad} is made of a polyethylene 
wherein
{ HEAD ~ A piston pump } 17 wherein { TAIL ~ said wear pad } is made of a polyethylene
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH