{HEAD ~ The blister} when in its piercing position is interposed between {TAIL ~ the delivery channel} and the connection channel  
is interposed between
{ HEAD ~ The blister } when in its piercing position is interposed between { TAIL ~ the delivery channel } and the connection channel
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH