, it will be appreciated that changes can be made, such as the substitution of {HEAD ~ materials changes} in {TAIL ~ shape}, and tee sequence of manufacturing steps, without departing from the spirit thereof 
, it will be appreciated that changes can be made , such as the substitution of { HEAD ~ materials changes } in { TAIL ~ shape } , and tee sequence of manufacturing steps , without departing from the spirit thereof
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH