The combination of the cap and connecting sections is inserted into {HEAD ~ the hollow} which is provided with an opening through {TAIL ~ its cover} 
The combination of the cap and connecting sections is inserted into { HEAD ~ the hollow } which is provided with an opening through { TAIL ~ its cover }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL