The outer peripheral side honeycomb unit has {HEAD ~ an outer peripheral cell wall} forming {TAIL ~ the outer peripheral surface} of the outer peripheral side honeycomb unit 
forming
The outer peripheral side honeycomb unit has { HEAD ~ an outer peripheral cell wall } forming { TAIL ~ the outer peripheral surface } of the outer peripheral side honeycomb unit
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH