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