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 {HEAD ~ the shape} of {TAIL ~ the fastening surface} is different from the shape of the engagement surface 
of
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 { HEAD ~ the shape } of { TAIL ~ the fastening surface } is different from the shape of 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 HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH