Further, with the metallic parts 11 and 21 in the coupled state, the longitudinal dimension L is greater than the transverse dimension S and the assembly of the metallic parts 11 and 21 is roundish as a whole, so that when the coupled metallic parts come into contact with the users body, they will automatically roll thereon until they assume a transverse position, i.e., a position in which {HEAD ~ the coupled direction} of the metallic parts extends along {TAIL ~ the users body} 
Further , with the metallic parts 11 and 21 in the coupled state , the longitudinal dimension L is greater than the transverse dimension S and the assembly of the metallic parts 11 and 21 is roundish as a whole , so that when the coupled metallic parts come into contact with the users body , they will automatically roll thereon until they assume a transverse position , i.e. , a position in which { HEAD ~ the coupled direction } of the metallic parts extends along { TAIL ~ the users body }
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 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 HEAD OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL