The number of {HEAD ~ guide bars} in {TAIL ~ each circular concentric series} increases from the radially inner series to the radially outer series of guide bars 
in
The number of { HEAD ~ guide bars } in { TAIL ~ each circular concentric series } increases from the radially inner series to the radially outer series of guide bars
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH