{TAIL ~ A linear ball bearing unit} 1, wherein {HEAD ~ said retaining side covers} are made of a sintered metal 
{ TAIL ~ A linear ball bearing unit } 1 , wherein { HEAD ~ said retaining side covers } are made of a sintered metal
TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH