{HEAD ~ Each} of {TAIL ~ the lateral surfaces} 10 is formed with a rectangular fixing recess 12 reaching the top surface 11 and the bottom surface of the main body 1 
of
{ HEAD ~ Each } of { TAIL ~ the lateral surfaces } 10 is formed with a rectangular fixing recess 12 reaching the top surface 11 and the bottom surface of the main body 1
HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH