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