a hub half forming {HEAD ~ the support body} and {TAIL ~ the hub halves} collectively defining an interior space, 
a hub half forming { HEAD ~ the support body } and { TAIL ~ the hub halves } collectively defining an interior space ,
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH