{HEAD ~ The assembly} 1, wherein the casing and {TAIL ~ the collars} are made of composite material 
wherein
{ HEAD ~ The assembly } 1 , wherein the casing and { TAIL ~ the collars } are made of composite material
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH