This permits {TAIL ~ introduction} of a resilient cap, which will secure the connecting sections within {HEAD ~ the hollow} and allows otherwise trapped air to escape readily through the opening 
This permits { TAIL ~ introduction } of a resilient cap , which will secure the connecting sections within { HEAD ~ the hollow } and allows otherwise trapped air to escape readily through the opening
OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH