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