In addition, the present apparatus comprises {TAIL ~ surface interfaces} between a slidable sleeve and a mandrel to minimize a probability of mandrel and sleeve separation during the plungers ascent phase and a risk of {HEAD ~ plunger stall} 
In addition , the present apparatus comprises { TAIL ~ surface interfaces } between a slidable sleeve and a mandrel to minimize a probability of mandrel and sleeve separation during the plungers ascent phase and a risk of { HEAD ~ plunger stall }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD