First of all, the pressing roller unit or {HEAD ~ a plurality} of {TAIL ~ such units} is located at the appropriate location or locations 
of
First of all , the pressing roller unit or { HEAD ~ a plurality } of { TAIL ~ such units } is located at the appropriate location or locations
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH