a fastening surface positioned opposite the engagement surface and configured to receive the internal component, the fastening surface having a shape in accordance with a portion of the internal component, wherein the shape of the fastening surface is different from {TAIL ~ the shape} of {HEAD ~ the engagement surface} 
a fastening surface positioned opposite the engagement surface and configured to receive the internal component , the fastening surface having a shape in accordance with a portion of the internal component , wherein the shape of the fastening surface is different from { TAIL ~ the shape } of { HEAD ~ the engagement surface }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD