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