Once hollow closed end needle 10 has been inserted into place in flexible closed end sheath 4 stopper 26 is slid over hollow closed end needle 10 in the direction of {TAIL ~ button} 25 until teeth 27 and 28 grip around cylindrical surface 31 of {HEAD ~ element} 32 a of button 25 
Once hollow closed end needle 10 has been inserted into place in flexible closed end sheath 4 stopper 26 is slid over hollow closed end needle 10 in the direction of { TAIL ~ button } 25 until teeth 27 and 28 grip around cylindrical surface 31 of { HEAD ~ element } 32 a of button 25
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 OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH