providing a syringe plunger having {TAIL ~ a first lock element} located only at {HEAD ~ its distal end} 
providing a syringe plunger having { TAIL ~ a first lock element } located only at { HEAD ~ its distal end }
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD