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