The chopper module 1, wherein {HEAD ~ the plurality} of longitudinal channels comprises {TAIL ~ four longitudinal channels} 
comprises
The chopper module 1 , wherein { HEAD ~ the plurality } of longitudinal channels comprises { TAIL ~ four longitudinal channels }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL